One size fits all! Just inflate for the desire shape! (And in case of shipwreck, no need to fret. You will bob along prettily while everyone else is stuck with those horrendous life preservers.)
Research is one of my favorite parts of the writing process. The little details you discover can do so much to flesh out your story. However, I’ve found some of the best gems are to be found when you can go explore where your story is set (especially when the place hasn’t changed much from the time when the story is set.) Even if they never make it into your story (such as the above treasure), it gives you the feel for the place and era. And sometimes a good laugh.