For the LEDs I got, they come in a pre-sealed sleeve meant for marine use.
https://www.amazon.com/gp/product/B00ILYUQVA/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1
Last year I did a redo on an old 14' Starcraft that my dad had bought 25 years ago when I was a kid. The boat had been starting to fall apart so I tried to think about all the complaints I ever had when fishing and used that for my design and inspiration. I spent a ton of time on this site...