Regarding the Panerai “Trittico” (a set of diving tools for the wrist: watch, compass and depth gauge) – the diver didn’t necessarily wear all three instruments at once when working as a team.

The actual diving was done in pairs where the divers swam one above the other. The top diver had a watch and a compass and was the “navigator”, while the bottom one had a watch and a depth gauge and was the “controller”.

These divers were connected by a cord in order to maintain a close distance. Also this was important to stay together during night missions in darkness or because of a strong stream. 

These cords were connected to the divers by means of a leather strap. In the pics are 2 types of cords, the short one is about 2.5 meters long and the long one is 5.0 meters.

Photo credits to Assaf Burstein from Israel