We took the Oregon Scientific MP120 to the local lap pool, clipped it to the bathing suit, and took it for a swim. Although it operated perfectly while immersed, the earbuds seriously diminished the experience. They sounded tinny, flat, and weak, and their rubber, pluglike tips didn't create a waterproof seal in our ear canals. Thus, as we submerged and surfaced, audio alternated between muffled and loud. One could argue that sound quality isn't a crucial consideration when you're getting wet and wild, but we found the frequent tonal changes distracting.
If you plan to hit the gym before hitting the pool, you can remove the rubber tips from the earbuds and enjoy slightly improved audio, but the larger-than-average 'buds get uncomfortable in a hurry. Better you should plug in your favorite headphones, as we did. Sound quality went from mediocre to stellar. Of course, without the waterproof connector, the MP120 becomes an ordinary MP3 player, unable to safely get wet.
Given the MP120's reasonable price and watertight design, we're willing to overlook the stiff buttons and the lack of DRM support. Even the screw-on earbud connector is an understandable concession. But the AM-quality audio that dribbles from those earbuds makes the Oregon Scientific MP120 hard to recommend.