DIY hydrophone (not good)

This is my hydrophone creation that isn’t working properly. My current method is to connect this to the Microphone Input of a Sharp MiniDisc Recorder (MD-MS701H) and record this way as it was the only portable method I had especially with my Edirol digital field recorder was out of action.

This home-made hydrophone seems to be fine when using indoors but something isn’t right when I record outdoors..

Another failed recording attempt by Deptford Creek. The audio is taken from the internal iPhone microphone.

Behind-the-scenes of more hydrophone making: