Craving more advanced dives? These eight sites are out of reach for rec divers and will test your tec-diving skills. But please, for tec trained divers only.

CORDELL BANK NATIONAL MARINE SANCTUARY

All visitors need a permit to experience this lush, colorful offshore environment north of Point Reyes, California, where the bottom and its collection of invertebrate- covered rocky outcrops ranges between 130 and 200 feet. The nonprofit known as the Bay Area Underwater Explorers, or BAUE, holds such a permit, bringing back reports that this area is thriving with life — “absolutely stunning.”

RONALD B. JOHNSON VIETNAM VETERANS REEF

The placement of this 226-foot freighter off Pompano Beach, Florida, is so bizarre that no artificial-reef program could have planned it. It sank perpendicularly on top of a second wreck, the 130-foot dredge boat Corey N. Chris, lying in the sand at 270 feet. Perhaps most unusual is the experience of swimming underneath the RBJ and hearing it creak overhead in the currents.

SHOTAN MARU

This 285-foot cargo steam ship, part of the Truk Lagoon fleet, sits at 180 feet at its deepest point. Inside, the wreck stands as a museum to the necessities of war, still containing ammunition, fuel drums, and beer and ink bottles. If those items don’t tell enough of a story, try staring down the gun still on the stern deck.

NORNESS

Off Rhode Island in the neighborhood of the SS Andrea Doria lies Norness, a 489-foot tanker lying on the bottom at 275 feet — 25 feet deeper than the more-famous ship. The biggest highlight is that it’s doable as a day trip from Montauk, New York, whereas Andrea Doria is far enough out that it requires an overnight on-site. Of the Norness, only the stern has been located, but that section alone is far less collapsed than the Andrea Doria.

USS AARON WARD

Thanks to its depth at 230 feet to the sand — out of reach of most looters — this 348-foot destroyer is one of the best-preserved remnants of the Solomon Islands’ involvement in World War II. Find it north of Guadalcanal just off the Florida Islands; its cannons, torpedoes and screws still remain.

USS MONITOR

Timing — aka waiting for the perfect Atlantic Ocean conditions — is the biggest hurdle in reaching this 173-foot iron-hulled steamship found 240 feet deep off Cape Hatteras, North Carolina. It sunk in Civil War-torn 1862, along with 16 crew members. In 1973, more than 100 years later, the ship was located by a team of scientists. The site is the nation’s first marine sanctuary (designated in 1975); it is accessible to those with a permit, including Capt. J.T. Barker with the vessel Under Pressure.

M/V BIANCA C

The Andrea Doria of the Caribbean, this 600-foot former passenger liner off the island of Grenada lies in 165 feet of water. The ship is a treat for most metalheads because it’s in warm water with 100 feet of visibility as a norm. The biggest highlight for some is taking a “dip” in the lido-deck swimming pool.

CHESTER A. CONGDON

This 532-foot bulk steel freighter met its fate in 1918, sailing to the bottom of Lake Superior near Isle Royale. Now, tipped on its side, the ship lies at 210 feet at its deepest point. The ship is intact, from the bow to the pilothouse to the stern, with details such as a wheelbarrow in the boiler room, and the engine controls.

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