Is a vent required in a watertight enclosure?

Hi there!

We are currently building an ROV and have an inquiry on the watertight enclosure, specifically in closing it. Is the enclosure vent and plug required to be used in the watertight enclosures? Or would it be okay if we just simply unscrew the end caps every time we need to open and close it? We are unsure if we could use another hole for a vent since most of our holes are already dedicated for wiring.

Any response to this question would be highly appreciated. Thanks!