See, I believe that in my case, when I have another portal that opens into a sub-oceanic location, my general urge is to pop back to the nether and simply keep going in the same direction for another chunk of time before building yet another portal to go back to the surface and see what's up.

Connect those up with minecarts that are self-propelled, and you can go a long way and find a lot of resources without much effort, which I find incredibly handy. It's also a good way to dip in and out of various biomes, but you might want to create a node map of what's near each of those transport gates if you plan on using them regularly.