Forgot to share but we made it out to Dry Tortugas NP last month, one of the more remote and least visited national parks in the US. It is on a small island about 70 miles west of Key West, only reachable by personal boat, ferry, or sea plane.
We took the ferry which is about a 2.5 hour trip each way. The ferry seats 175 passengers. We were warned it could get rough and to be prepared so we all took dramamine in the morning before boarding. It did indeed get rough. Seas were about 10' and we had a 10-15 knot headwind. The first hour was bouncy but bearable. The second hour got really rough, to the point where the crew told all passengers to remain seated and to only stand if accompanied by a crew member. The crew members spent about an hour going around to check on passengers, handing out barf bags (many of which where used) and cleaning up if necessary. My son had a particularly rough time and really didn't want to make the return trip. I wasn't feeling great, but I held down my breakfast.
Once we arrived at DT we realized the trip was worth the hassle. The fort is impressive. It was built in the early 1800s to project power into the gulf, but was an engineering boondoggle and hellhole in every way imaginable. It only ever saw limited use as a prison during and after the civil war (it's most famous occupant was Samuel Mudd). The fort was impossible to supply and maintain given its location. And, the ground couldn't support its weight, so they stopped building it in the mid-1800's. It is crumbling in some spots, but holding up well in others.
Fortunately the ride back to Key West was smooth with no issues.
I don't think I would ever return, but it is definitely worth the trip at least once. Some people go out and camp for 3 nights. Others spend time snorkling around a shipwreck and coral reef. The water temp was in the 70's so a bit too cold to snorkel so we spent the bulk of our 4 hours of available time exploring the fort. If you do go, get a prescription for the patch that goes behind your ear to prevent sea sickness. Several people recommended it to us and I wish I had listened to them.