Small handheld depth sounder. of extremely simple operation. particularly intented for pneumatic or dinghy sailors. Equally useful to scubadivers : it gives depth indication relative to the bottom. distance to a rock or to an underwater quay.  Totally waterproof. the Echotest II sounds up to 80 metres. and can be used at a maximum depth of 50 metres. Echotest operates only when immersed.