Where we live, it's hot and humid and a lot of salt breeze. It really does depend on all these details and then actual nearness and exposure. Something that is 30 meters from the water and exposed lasts 1/4 of the time as something 100 meters from the sea with a wall between. Keep your gear as far out of the sea breeze as possible.
I found that keeping dust down also really helps. In addition, I have sealed boxes with gun safe dryers in them for gear that is stored. The dryers have silica beads and you plug 'em in to dry 'em out, then into in the sealed bin with the gear. Rinse and repeat monthly.
For my computers, router etc, stuff that can be kept on, I keep as much as possible inside a cabinet with limited air flow (not sealed) and let the heat they generate drive the moisture off. Really helps. Probably ten degrees hotter inside and I'm convinced that the heat damages the gear far less than the moisture that is driven off.
Stuff that is in the open, keep the air moving so that dampness does not accumulate. Fans.
Be prepared to replace as needed.