Jimmy Pettit is a 40-year-old construction project manager. He and his family live near San Diego State University. He owns an MP3 player made by iRiver, along with a waterproof housing and submersible headphones designed by local firm H2O Audio. Pettit has 28 songs downloaded into the iRiver's memory, all of them ripped from his collection of CDs.

"My wife made the jump and made the investment for me for a Christmas gift. We had talked about it...sometimes when you're out surfing with friends you want to spend time with your friends, but when you're out there by yourself...I saw a guy on a kayak with one. You're starting to see more of them around. A lot of people don't consider that you can bring music out into a wave."

He describes the waterproofing device. "It's a clear plastic housing that's got, like, a locking hinged door that seals it all in. It's got jacks and everything that are fully waterproof and sealed. So you pull the [MP3] unit out and download music off your computer. It [the waterproof exterior] has got little buttons on it that go through the housing and operate [the MP3 player inside]. It's got these little rubber buttons that have little rubber boots on them that go through the case."

Pettit has tried a number of unsuccessful waterproof designs. "When they came out with the first-generation Walkman by Sony, they came out with this one that was supposed to be waterproof. I mean, you could maybe go in the shower with it, but you could never really submerse it. I remember a friend of mine stitched a pocket into his wetsuit and put it [the Walkman] in there -- it just never really worked."

How has being able to listen to music while surfing affected you?

"Surfing's a sport where everything's constantly changing. No two waves are exactly the same. They go at different speeds. They're in different shapes. There's a rhythm involved. You have to kind of put a rhythm to it to make transitions from one point to another. It's kind of groovy to put music to it. You can watch surfing in a movie and there's music to it. But when you're out there surfing, the sound is more...the water. When you can incorporate music you can take it to the next level. It makes it a lot more fun.

"I'm the only person in my immediate group that has one right now. But I have a buddy of mine -- if he asks me to borrow it one more time, I'll tell him he's gotta go get one of his own. We play tug-of-war with it."

Any downside to listening to music on the waves?

"No. You know what? It's been a good experience. So far, I haven't, like, crashed into anybody because I wasn't paying attention...because I was rocking out or anything. But the really good thing is, like, sometimes when you're out there and you're in between sets and you can float on your back...the system uses the water to make the sound really clear and pure. It's the most awesome sound system when you're completely under water."

I confirm this with H2O Audio's inventor, Kristian Rauhala. "We designed the dive product to do exactly that." He explains that since water is a sound conductor, with the headphones on under the surface, "It sounds like the music is coming from everywhere."

"I [surf to] a pretty broad mix," says Pettit. "I've got Foo Fighters, Ella Fitzgerald...and some Jack Johnson."

Johnson is a singer-songwriter surfer. "I wonder if he owns one of these things," I say.

"I don't know," says Pettit. "He should."

Jimmy Pettit's Top Ten:

1. Ben Harper, "Forgiven"

2. Van Halen, "Cabo Wabo"

3. Louie Prima, "Just a Gigolo"

4. Metallica, "Hero of the Day"

5. Audioslave, "Like a Stone"

6. Pearl Jam, "Dissident"

7. Sublime, "Pawn Shop"

8. Django Reinhardt (untitled)

9. Offspring, "She's Got Issues"

10. Unknown slack-key guitar track