You can take your iPhone 4 under water for amazing shots if it has been armored by waterproof case, but if not, the waterproof plastic digital camera may be a nice alternative.
This is a compact digital camera, as shown in the images, the digital camera features a clear waterproof housing in order that you can use it to capture wonderful photos under up to 100 meters of water, while the plastic lens lets you create amazing lo-fi images. The waterproof camera also comes with 16 MB flash memory and a SD card slot supports up to 2GB memory card for your storage. Moreover, the 10 second self-timer allows the plastic camera to get all targets also including yourself in one picture.
The waterproof plastic digital camera is priced at $35 USD. If you’re interested, jump to photojojo for more details. Additionally, if you also like 35mm camera, you might like to check another underwater camera.