When survival is the goal, greater security comes with numbers. Here, we're taking a closer look at schools and shoals—plus, we'll tell you how to capture the best underwater photos.
Want to add a little adrenalin to your diving? See if you're ready for the challenge to dive the world's fastest tidal current: Saltstraumen in Norway.
Would you like to help raise money for marine-conservation research? REEF, a grassroots organization that aims to protect marine ecosystems, is accepting donations.