start with spray, cotton wool pulled out, for bases shower tiles/curtains,"ripple"glass and plastic, ripple side down flat up is best for waterline models but cotton wool covers gaps , take photos of sea and print, check/search model railway "water", that should keep you going for a while!
Please, your suggestions for learning how make or buy sea surfaces.
I've never attempted a water surface for a realistic sense of a vessel in water. At most I've done blue cloth! Please, can you recommend a source where I can learn to make [or acquire pre-made] sea surfaces?