Not sure I got that right, but you avoided the ocean biome as well as sailing close to the swamps...? I agree, the swamp is the next step on your journey and thus it is inevitable being able to deal with those, altho such an island with a draugr village might be a tough starting point.
Personally I'd suggest to scout for other waterways (unless you were sailing in an enclosed 'lake' rather than an open ocean - even if there is a small ocean biome in the middle of it), you'll need to deal with the ocean sooner or later anyway. I'll give you a tip if you want:
Take your bow with you, eat good food (you should have access and be using the ones with carrots when looking for the elder by now) and have your bow skill at around 30+. You could just sail around for a bit in the ocean biome to see what might happen during different weather or day-/nighttime. Just make sure you are actually sailing/moving with your ship and have enough stamina and can quickly return to a safe coast if needed. If you will do this, I'm sure you'll be fine by slowly testing out your own capabilities.
There's always several ways to get to one such destination. If your map should have plains at 3 directions from your spawn (just as an example), you might need to find a way around those or take the mats for a boat/portal with you and scout for another connection to the ocean from where you can start scouting again.
That much for your actual question, but I have one more note to make if you don't mind:
You might save yourself a good portion of frustration if you got yourself the bronze weapon & shield, in case of 0%-brain-moments as described above :P That's not to make fun of you, but those might have helped.