This project was fun. After losing a Gopro Camera attached to a kite which crash landed in the lake where i lived, I decided to buy a down scan imaging device to try and find it.
Yes , the down scan imaging device did cost 3 x times the amount of the Gopro but hey, this was the more fun approach.
I realized that finding it was not only the first problem but retrieving it was the next issue. So i knocked up a grabbing pneumatic hand on an extendable arm. Mounted on a rig which could be lowered to a depth of 12meters it was also equipt with underwater spot lights and cameras .
I never did find the Gopro. But i did find keys, mobiles, eels and fish. I also had lots of fun in the process.