A well know maritime technology company in Norway, Simrad (presently part of Kongsberg Maritime, was based in Horten and built echolocation and sonar equipment. The first echo sounder was invented by Norwegian Hans Sundt Berggraf from Stavanger. However as seems typical for any technology invention in Norway he could not obtain money to patent it. So German Alexander Behm patented it several years later.
Above is a scientific echo sounder.
This is a Simrad sonar. Sonar is different form echo sounder’s in that the latter only looks downwards towards the sea bottom. A sonar sends out sounds signals in many different angles and listen for the echo. In that respect it works much the same as radar. Except it uses sound waves instead of radio waves.
HPR Hydro acoustic Position Reference System
This black box with yellow buttons is a Simrad HPR. It is used in combination with acoustic light houses. By having each acoustic sender at the sea bottom at known position, one could listen for acoustic signals from these and use triangulation or trilateration to calculate ones position at sea.
Simard developed this Hydro acoustic positioning system from 1975 and had significant commercial success from it. It was important for Norwegian offshore oil industry which they had just started building in the 70s.
Wireless telephony has always been important in Norway due to the significance of shipping and maritime industry to the Norwegian economy. It helps explain why NMT Nordic Mobile Phone network as the first cellphone system in use in the world. In the 80s tiny Norway had the largest cell phone market in the world.
Here are some of the later equipment. But I forgot to read what exactly they were. I assume these are newer sonar equipment.