Keep them dry and keep them warm, in that order. Sea spray in a Zodiac is the main threat, so carry electronics in a roll-top dry bag or internal dry sacks rather than trusting a backpack. Cold drains batteries much faster than you expect, so carry spares somewhere warm, ideally an inside pocket against your body.
Confirm the outlet type and voltage on your ship with the operator rather than assuming, because it varies between vessels. Bring the adapters that ship actually uses, plus enough charging capacity for the number of batteries you're running.
One airline rule that catches people: spare lithium batteries must not go in checked baggage. Follow the current limits for your airline and pack them in your carry-on.
Condensation is the other quiet problem. Coming from a cold Zodiac into a warm ship fogs lenses and sensors. Letting gear warm up gradually inside a sealed bag helps.