1. H20 AUDIO FOR iPOD NANO H20 Audio's waterproof case is helping the iPod, already king of the terrestrial digital audio market, conquer the other three-quarters of the world. Tune in up to ten feet under with the new Nano version. The headphones ($40 extra) sound a little hollow, but that's a small price for taking your playlist beyond the beach. $80; www.h2oaudio.com

2. NIXON CHANNEL T Whether you're catching waves or dinner, it's crucial to know tide times. The Channel T delivers the data in a stainless-steel package that's depth-rated to more than 300 feet and comes with a seaworthy polyurethane band. The offset crown won't irritate your flexed wrist when you pop up on a surfboard. $180; www.nixonnow.com

3. SEA & SEA DX-75OG Tired of your dive partners calling bull on your alleged shark sightings? Show them proof with the DX-750G, a five-megapixel digicam that comes with a removable waterproof housing good to 150 feet. Shutter lag is a tad slow, so don't waste much time framing the shot when that hammerhead swims into view. $499; www.seaandsea.com

4. MOTOROLA i355 When I called my buddy to brag that I was sea-kayaking while he slaved away at a desk, I made sure to dip the i355 overboard so he could hear the waves. Then I put the drenched phone up to my ear to hear him cursing me—clear as a bell. The rubberized shell makes it a bit bulky. $90 with two-year service agreement; www.sprint.com