Potting a lithium batery pack?

foildrive uses some type of epoxy to pot their batteries for gen 2, I want to build a custom battery that may get exposed to seawater, any recomendations on a potting material to use?

i made without potting just stuck cells together with 3m 5200 for stability and vibration dampening as you cannot isolate the cells from contacting each other because of room that the pack will get way longer, which is not great idea to rely on cells heat shrink from the factory. potting definitely won’t let the cells to contact each other. I’m hoping to have the same result with a bead of that PU adhesive.