Imagine four or five dives a day, every day, for a week, every site different and most of them remote and pristine. See the cheerful crew fill your tanks, hoist your BC and practically carry you into and out of the water. Savor hot showers, hot towels, hot cookies and hot toddies or a cool rum punch, then an ample dinner, a glass of wine, maybe even a mint on the pillow.

Ah, the live-aboard experience. For one week you live like a millionaire aboard a custom dive yacht. Your world narrows to the company of 19 fellow adventurers. For seven blissful days, life is reduced to the essentials--dive, eat, sleep, in that order of importance. Your daily routine: snack, dive, breakfast, dive, snack, dive, lunch, dive, snack, dive, dinner (optional night dive in some cases).

There's simply no way to get as much incredible and varied diving packed into one week, and when you figure it might take two weeks at a land-based resort to absorb as much first-class nitrogen, it's no wonder that so many experienced divers we surveyed said, "Give me the choice and I'll go live-aboard every time. It's the way scuba--make that life--was meant to be." Here are 19 dos and don'ts that will help your cruise go even more swimmingly.

Do: Pack light. Don't: Pack a wardrobe worthy of Anna Nicole Smith.

If, in addition to your dive gear, you're packing more than one carry-on bag and a medium-sized piece of soft luggage, go back and repack with this rule in mind: half the clothes. Still too large? Go back and follow the rule again. If you're packing for the Captain's Banquet, the First Night Ball and Monte Carlo Night, forget it. Informality rules on the live-aboard--think swimsuits, shorts and T-shirts.

"My mistake was that I brought too many clothes and not enough swimwear," says live-aboard diver Pejman Khosropour of his first cruise. "I brought five pairs of shorts and two pairs of trunks, but I should have brought five trunks and two shorts."

If you want to impress with your wardrobe, the fashion gotta-have is simply the correct T-shirt, says Clay McCardell of Explorer Ventures. "The first day or two everybody will be wearing a T-shirt from the most exotic location possible."

To save additional luggage space, wear a sweater, one pair of shoes, one pair of long pants and one light jacket to the boat. With the room you save, pack these essentials:

• More exposure protection than you think you need. (The more you dive, the colder you get.) Take an extra layer, a hood or beanie.

• A save-a-dive kit.

• Surface signaling devices (sausage, horn, whistle, mirror, etc.)

• A spare mask.

• Adequate film and batteries for cameras, dive lights, Game Boy, etc.

• Sunscreen.

Pack critical and essential items like mask, regulator, dive computer and exposure suit in a carry-on. If the airline misdirects your luggage, the boat can't wait a day for your stuff to arrive.

Finally, use soft luggage. Even the largest boat cabins are a lot smaller than Motel 8 rooms, and there's no cargo space for hard suitcases. Soft luggage is a lot easier to stuff into a corner.

Do: Pick your room in advance. Don't: Plan on switching at the last minute.

Live-aboards have a limited number of cabins and they are usually booked solid. If you don't like your room, your only hope is to sweet-talk someone into swapping with you. Good luck.

The smart solution: Pick your cabin when you book. "Ask for a plan of the boat and ask questions," says Matthew Armand of the Aggressor Fleet. Think about boat motion (there's less near the center), proximity to noisy generators and compressors (usually in the stern), convenience to rest rooms and dining areas, stairs to climb and even traffic patterns.

"Amidships near the centerline of the boat is the best cabin location, minimizing pitching due to heavy seas. Avoid extremes of bow and stern unless your desire for privacy far outstrips your susceptibility to seasickness," says experienced live-aboard diver J.D. Barnett.

Whatever you do, don't sweat a less-than-ideal cabin or cabin mate. You really only sleep there. Most of the time you're diving, eating, preparing to dive, eating again or talking about diving.

Do: Make special menu requests in advance. Don't: Let a soda preference ruin your vacation.

Most divers describe live-aboard food and drink as ample, tasty and sometimes even elegant, but not "designs on plates" as one diver calls haute cuisine. Expect meat and potatoes, chicken and rice and veggies and salad, often served family or buffet style. There's no menu to order from, no room service, and few chances to make substitutions.

If you want something special--if you're a vegan, for example, or you'll only drink Heineken or Diet Coke from a can or can only tolerate a certain brand of organic soy milk--request it well in advance. The boat will try to accommodate you, but that special First-World luxury may be hard to find in a Third-World tienda. "We often provision from small islands and never know what the island will have from one week to the next," says Terri Huber, a reservations supervisor for Peter Hughes Diving.

The best option if you can't live without some taste treat: Bring it with you. Actually, most live-aboard divers find those refined tastes and familiar brands don't seem so important after a day or so of amazing dives.

Do: Prep your gear. Don't: Rely on the boat's gear locker to fix problems.

There are no dive shops at sea and most boats have limited repair and rental capacity. Have your gear serviced and prepped, then test it before you pack. Replace the battery in your dive computer. Inspect straps, buckles, etc. Also pack backup O-rings, spare parts and batteries for critical gear.

Do: Be nice to the crew. Don't: Think you're a king, just because they treat you like one.

Many divers are surprised at how hard live-aboard crews work under difficult conditions, yet are so cheerful about it.

Most crew members pull double and triple duty--your divemaster may take a turn serving dinner, entertaining guests or helping man the boat, so cut the crew some slack if things aren't always perfect. "You might be sitting there yelling at a guy for not giving you a clean coffee cup, and that's the guy who's going to be finding your life jacket if the boat's sinking," says McCardell.

As with most occasions in life, the more kindness and respect you give, the more you'll get. Small gestures can mean a lot to the crew. "Bring a new movie on DVD to share with the whole group," suggests Armand. "The crew, which is away from civilization for long periods, will especially love it and maybe treat you extra well. And it helps break the ice with the whole group."

On the other hand, crew members do sometimes screw up. If there's a genuine problem, inform the captain. He wants to know sooner rather than later. Then be patient. Remember, some other passenger may be demanding attention at the same time.

Do: Arrive early for dive briefings and meals. Don't: Hold up the schedule.

If everybody is going to get in all five dives, plus eat all the meals and snacks promised, there's going to have to be a schedule and everybody is going to have to stick to it--especially true when you're diving in groups from tenders. A good live-aboard rule is this: whether the line is for lunch or lifeboats, never be last.

This is particularly important when boarding the tender. Don't leave your fellow divers stewing in their wetsuits under the tropical sun while you get your act together. If your tender is late to dive, you and your fellow divers will be late to the showers, late to the lunch line ...

Being late has costs besides cold shoulders. You may miss dives, skimp on your surface interval and make mistakes because you're rushing to catch up.

Do: Tip generously. Don't: Stiff the crew.

The price of a live-aboard cruise includes your diving, food and lodging. However, it usually doesn't cover tips for the hard-working, multitasking crew that spends the week catering to your every whim 24/7 (see above). Tips are always an important part of the crew's income and they will earn every penny of it.

Bring cash--a typical amount is 10 to 15 percent of the package price--to tip the crew with at the end of the week. Budget for the tip money and set it aside before the cruise starts.

Want something special, like a personal dive guide all week? Ask for it and tip big, in advance.

Do: Be flexible about dive sites. Don't: Throw a fit if you don't get your way.

The fact that the group of divers on a live-aboard is smaller than at most land-based resorts cuts two ways. Good news: The captain will select dive sites to suit the interests and abilities of the majority of the group. Bad news: You might be in the minority.

Before you book your trip, ask about the make-up of the rest of the group. A large number of novices may dictate easy dives. A dive club may leave you feeling isolated. (Or you may join them and make a dozen new friends.) In any event, a skillful captain will give the minority at least some of what it wants, so speak up early.

Do: Buy trip insurance. Don't: Rely on the benevolence of the travel gods.

Political unrest, major weather or the wide-ranging "acts of God" could prevent a trip. If the boat can't sail, the live-aboard company will probably offer a refund or put you on another cruise, but you might be out airfare and other expenses.

If the boat sails and you're not on it, however, don't count on getting a refund. Most live-aboard companies have restrictive cancellation policies, because each slot represents such a large percentage of the week's revenue. Some will refund part or all of your fare if they are able to fill your room from a waiting list. Ask about the policy before you book.

The beauty of trip insurance is that it reimburses you for all covered losses regardless of the reason. It's highly recommended by all the live-aboard companies, and it costs just a small fraction (between four and seven percent of the package price) of the cruise. Some policies include additional benefits such as emergency medical care and evacuation. For details, check: www.accessamerica.com, www.travelsecure.com, www.travelsafe.com, or www.travel-guard.com, among others.

Do: Carry dive insurance. Don't: Think DCS can't happen.

Most live-aboards visit remote locations and provide the freedom to dive as aggressively as you dare. Should you come up bent, you'll need air evacuation to the nearest recompression chamber. The bill for the chopper ride alone will dwarf the tab for the cruise--many times over. Dive insurance is cheap. For annual premiums ranging from $45 to $99, you can get ample coverage for dive accidents and emergency evacuation costs. Sure, DCS is rare, but it can happen to any diver.

Do: Mind your gear station. Don't: Jump someone else's.

Even a spacious dive deck can get crowded with 20 divers and a handful of crew milling about before the dive. You'll be assigned a station to store gear and suit up. Keeping your station orderly and organized will go a long way to smooth operation.

When you surface from a dive, don't be tempted to drop your empty tank off in the first spot near the dive deck. Clear the platform and walk your tank back to your station so the crew can swap or refill everyone's tanks in time for the next dive.

If you can, choose a dive station at the end of a row. You'll get more elbowroom on one side. Avoid the dive stations near the entry or exit point, as other divers will be constantly squeezing past. "Better to be the one tromping all over other folks' fins than have them tromping on yours," says Barnett.

Do: Take a specialty course. Don't: Miss the opportunity to improve your skills.

"A good use of a live-aboard is to take a specialty course. Everything is right there, so you'll get through it quickly," says Armand. Added bonus: You'll have the chance to practice your new skills on five dives a day.

Do: Take motion sickness medication, just in case. Don't: Think it can't happen to you.

A lot of day-boat divers can boast that they "never get seasick," but a live-aboard provides a whole different motion environment. You'll be at sea for a week and even the biggest, most stable boats will experience some motion. Motion sickness meds are a good precaution until you're sure you've got your "sea legs." Start taking Dramamine (or whatever) the night before the boat departs. You'll sleep better and get a head start against any seasickness.

Do: Heed the warnings on the marine head. Don't: Flush anything you haven't digested first.

Marine toilets clog easily. Don't try to flush tampons or great wads of toilet paper. Enough said.

Do: Laundry in the sink. Don't: Expect laundry service on board.

A travel-size bottle of Woolite or other cold-water detergent allows you to wash swimsuits in the sink. Ask the crew where you can hang your stuff to dry.

Do: Ask about ship-to-shorecommunications in advance. Don't: Assume your cell phone will work.

Some might ask if you really need to check e-mail in the middle of an away-from-it-all vacation, but emergencies do arise. Some boats are better equipped than others, but that e-mail or phone call might cost you a lot. Don't count on cell phones to work far out to sea.

Do: Be candid about your diving skills. Don't: Believe your buddy's boasting about how rugged the diving is.

Some live-aboards do visit remote and challenging dive sites, but almost all trips are designed for average divers. If you're concerned about sites being more than you can handle, ask before you book or seek appropriate training before the cruise.

Do: Your scuba homework. Don't: Ignore the briefing.

Research the area before you go, and not only the diving conditions but also the endemic marine life. Make a list of fish and coral you want to see and challenge yourself to find it. If you're in a hunt for rarities, follow the advice of the dive guides about where to go on a particular site. "Trust the crew," says Armand. "They dive there week in and week out and they know where things are."

Do: Make the most of your vacation. Don't: Feel pressured to make every dive if you don't want to.

Don't feel obligated to make every dive, just because you paid for it. You paid for a vacation, so read that novel instead if you feel like it. Listen to what your body wants to do.

It doesn't hurt to take a day off from diving, or at least an afternoon, at mid-week. You've been absorbing a lot of nitrogen and losing body heat and energy. A break will improve your enjoyment of the rest of the week.

Blue Blood or Blue Collar?

Q: What's the difference between the high-end (read: more expensive) live-aboards and the budget cruises?

A: Typically, the high-end live-aboards are larger boats with double cabins compared to the multiple berths on smaller, budget-oriented vessels. "The big tradeoff is privacy," says Beth Olveira, a booking agent with the company that owns Blackbeard's Cruises (small boats) and the Aquacat (a large one).

On larger boats, bathrooms are typically en suite. There will be closets and drawers, but small ones. All cabins will have reading lights, most will have air conditioning and some will have individual TVs and VCRs.

"Blue collar" is one diver's term for the smaller, less luxurious live-aboards. The number of dives and the quality of food is not radically different from the high-end boats, but sleeping accommodations are usually bunkhouse style. Sometimes a couple dozen bunks--uppers and lowers--are arranged along a passageway. Sometimes they are grouped in three or four cabins. You sleep on one side of your bunk, next to your bags, and have a shelf or net for small stuff, and maybe a reading light. A curtain gives a hint of privacy. If you've seen Pullman sleepers in an old movie, you've got the picture. A few of these bunks may be smaller than others and odd-shaped--more reason to reserve ahead.

10 More Dos and Don'ts

Do:

• Research departure taxes, park fees, etc. before you go, so you're not surprised.

• Learn something about the local culture.

• Bring enough film and batteries. They may be available on-board, but they will be expensive.

• Bring ear plugs if you're a light sleeper. Some machinery noise is inevitable and your cabin mate might snore.

• Bring your snorkel. Keep it on hand for those once-in-a-lifetime encounters with whale sharks and mantas. Bubble noise will scare them off.

• Bring anything you might need from a pharmacy. There's no drugstore at sea.

• Process your first few rolls of film onboard to ensure camera settings and strobes are working. But ...

Don't:

• ... process all your film onboard, says photo pro Stephen Frink. It's expensive and the chemicals may not be changed as often as they should be.

• Worry about sand flies, mosquitoes and no-see-ums. You'll be anchored offshore and out of their flying range.

• Worry about theft or crime. This is one resort surrounded by a moat! You won't need to lock doors or lockers.