I can tell you that as a player I think I'd rather be shipwrecked than imprisoned. Both are interesting situations to be in, but I think the possibilities of a shipwreck are more intriguing. Assuming you're going for a deserted island thing I think it'd be super exciting to have a small island to explore and survive on until the party was either rescued or found a way to escape. Heck, if there are some ruins on the island those could be cleared and the party could eventually return and make the place a kind of secret hideaway or stronghold. Dang I really like that idea. I'm going to have to use it.
Everyone that spends some time here giving, deserves some rep. My pleasure to be the first to give it. Thanks for stopping at my page and dropping a note. As to my suddenly overpowering players, I think that may be less about having some back-up NPC's/creatures and more about the fact that they have been all about the gear. And I have let that happen. Kicking it up a notch
shouldn't be a problem though. I am torn between the idea of shipwrecking or imprisoning them.
Thanks for my first rep point, good sir!
maxsdaddy, I noticed a post of yours in geamon's "Nentir Vale - Points of Light- Battlemaps" thread about how your players are overpowering the creatures you have prepared for them. It might be worth your time to create a handful of standby npcs and monsters that you can throw in when you feel things are going too easily. Having those standbys pre-prepared can really save you from scrambling during a session. That way you can concentrate more on getting a feel for what your players can handle and less on those last-minute ways you can make things more challenging.
Hope that suggestion is helpful to you. Happy gaming!