Easiest to access by helicopter, this harder-to-access dive site is teeming with life—thanks in part to its relative seclusion away from the masses.

This wreck, dating back to 1921, isn't the easiest to get to. But once you do, you'll be treated to an abundance of life.

Once a year, divers of all skill levels gather for a weekend of frigid diving in one of Iowa's frozen-over lakes.