I was a technician and diver on the
Bathyscaphe Trieste II which had hundreds of EO connectors, up to 4 pins/8 contacts. EO connectors were retrofitted to the boat during a major overhaul after the Scorpion ops (search and documenting the Scorpion submarine). EOs were chosen because they can be mated and unmated underwater. It took half a day to get the Trieste out of the water in order fix a submerged electrical cable or system before (unless they had a large service loop that would reach the top deck).
The caveat is you must be careful not to unmate powered circuits in salt water or certain connectors with two-contacts/pin. Unless the circuit is carefully designed, it is possible to damage circuits as contact two swipes against contact one when the connector is unmatted.
Even low voltage circuits will erode contacts over time and/or damage electronics. Short-term unmating simple low voltage and amperage circuits in salt water like strobe sync cables to cameras, are fine. I did see a high voltage and amperage DC connector from the batteries that was accidently unmated that melted before the over-current protection kicked in.
We found that dipping the EO pins in the end of a tube of silicone grease before mating dramatically increased the life of the connector and virtually eliminated corrosion on the beryllium copper contacts. Aside from coating the pin evenly all the way around, it was far easier than trying to apply the lubricant with your finger.
It was common practice to leave unmated and unpowered EO connectors exposed to salt water for up to 5 days. Divers would carefully clean corrosion from male contacts (pins) with mild abrasives before mating. We very rarely had to clean contacts on the female side of the connector because resistance was too high.