Quick Take: Take the plunge with the H2O Audio Oceanic DV-X, an accessory that lets you use your MP3 player on a diving or snorkeling trip. The kit provides waterproof housing for any iRiver 300-series player and earphones made specifically for underwater listening, so you can hear your favorite tunes or take an audio-guided tour of wreck sites or sea life. Operating at depths of up to 200 feet and featuring large external controls, the DV-X is a unique ocean-friendly add-on to any underwater gear setup. The major pitfall of this cool gadget: price. The accessory alone will set you back $350. If you don't already own an iRiver, check out Oceanic's other configurations, which include the MP3 player. (However, these options don't necessarily reflect a price break on the iRiver, so be sure to price the accessory and player separately.)