Trumpy,
Our immersed lighting has it's own fairly stringent requirements in the NEC art 680., Either 'dry nitch' or 'wet nitch' would specifically apply.

Our weather/water proofing would be dictated by the definition of dry/damp/wet area's throughout the NEC, with the appropriate materials required per listing/rating.

bodily immersion vs. associated electrically protective devices such as our GFI ( 4-6 ma) works a little funky here.

there are many situations where one can, by code, get away with normal ( non-GFI) protection. One such instance is a hard-wired pool, 3Ph motors,or pool heaters.

This i make no claim to rationalize.... others may imbellish... [Linked Image]