Detail shots
Close up details taken during your sailing adventure always look great in a gallery of shots. The detail could be parts of your boat, an ice-cold bottle of beer complete with beads of condensation, or a bit of driftwood on the beach. Your choice of lens will help dictate what will be shown.
If you choose a wide-angle lens you can get super close to your detail and get some background information too, though bear in mind the Gopros have a fixed-focus lens so will not focus very closely. Make sure you focus on the detail. However, if you would just like a really close-up shot of a certain detail, go for a longer lens. Both methods will give you good results.
Think about your light source, too. Early morning or late afternoon light is lovely. And if your detail has some nice texture to it, choose an angle where the sunlight hits the detail at an acute angle to emphasise that texture. For more advanced DSLR users your choice of depth of focus will really depend on what you want to achieve. I suggest starting with a very large aperture for a small depth of focus to isolate that detail from its background.