A small, waterproof, flash-based MP3 player sounds like a nifty idea, and this is what Nu has tried to create in their latest digital music device, the Dolphin. However, while the idea may be a good one, the execution leaves a lot to be desired, as the player suffers from poor audio quality and fiddly controls.

Sporting a slim, cylindrical design complete with orange straps to secure it to your goggles, the Dolphin is clearly designed with swimmers in mind. Every part of the unit is waterproof, from the headphones to the device itself. It is constructed from a combination of lightweight metal and rubber and the only opening, the headphone jack, is secured by screwing the headphones into place and sealing it with a rubber ring. We tested the Dolphin underwater and experienced no performance issues; it continued to operate perfectly hours after being submerged. It is capable of going to a depth of one metre for up to 30 minutes.

However while the device does deliver on its promise of waterproof music playback, the rest of its features are very poorly implemented. The biggest problem is the quality of the audio. To put it simply, this is the worst sounding MP3 player we've ever heard. Regardless of whether you are swimming or not, the Dolphin sounds terrible. The bass is totally bloated, completely overshadowing other elements of the music, and everything is extremely distorted, to the point where most of the detail in our music was lost.

Furthermore, this problem can't be easily rectified using third party headphones, as the provided headphones are waterproof where as third party replacements are not. However, even if you could find waterproof third party headphones, it wouldn't make any difference since the Dolphin uses a 2.5mm stereo jack rather than the standard 3.5mm size and no adapter is provided.

The unit has no screen, and only the most basic of controls. The buttons are all housed on the bottom of the unit, in a black, rubber circle. There are track skip and volume controls and a power button, and that is it. We wouldn't mind the simplicity so much if they were easy to use, but unfortunately they are extremely small and packed together very tightly, making the interface quite difficult to operate. This is only exacerbated by using the Dolphin under water, as it is a nightmare to try and use when you can't see the buttons.

Sadly, since there are no playlist, shuffle or random playback modes, you need to rely on the buttons as your only means to find your favourite songs, making the overall user experience quite irritating.

We also had some problems with the headphones. They are designed similarly to canalphones, with a long rubber tip that slides deep into the ear canal. However they are quite a bit longer than most other canal phones, and to get a proper seal you must push them extremely deep. We found this quite uncomfortable and a little painful, although it really depends on the size and shape of your ear canal.

The unit only supports MP3 and WMA formats and files can be uploaded from a PC via a standard drag and drop interface, with no software necessary. It connects to your PC via the headphone port, which also doubles as a data connection using the included headphone to USB cable.

Overall, the Dolphin is a poor quality device. If you really can't live without your music underwater, or if you want some music to amuse you while swimming laps at the local pools, then perhaps it will satisfy you. However, audio quality, lack of features and fiddly controls mean we have to recommend looking elsewhere.