Bottom or bay-cable hydrophone arrays having any of the following: (a) Incorporating hydrophones specified in VII.A6.002 or a hydrophone with a hydrophone sensitivity better than 180 dB at any depth with no acceleration. (b) Incorporating multiplexed hydrophone group signal modules having all of the following characteristics: 1. Designed to operate at depths exceeding 35 m or having an adjustable or removable depth sensing device in order to operate at depths exceeding 35 m; and 2. Capable of being operationally interchanged with towed acoustic hydrophone array modules; or (c) Incorporating accelerometer based hydro-acoustic sensors. Technical note: Accelerometer-based hydro-acoustic sensors having all of the following: 1. Composed of three accelerometers arranged along three distinct axes; 2. Having an overall ‘acceleration sensitivity’ better than 48 dB (reference 1 000 mV rms per 1g); 3. Designed to operate at depths greater than 35 metres; and 4. Operating frequency below 20 kHz. Notes: 1. Does not apply to particle velocity sensors or geophones. 2. Also applies to receiving equipment, whether or not related in normal application to separate active equipment, and specially designed components therefor.