To update some of my reviews from my previous discussion on plus size travel wear.
https://community.ricksteves.com/travel-forum/packing/plus-size-travel-clothes-for-women
Recently I needed a new swimsuit for my trip. I was planning on boating and snorkeling (as well as pool time) and wanted something with a rashguard and shorts for a bit more coverage. I tried the swim separates from Superfit Hero, which worked great. They have two-piece swimwear, and they are the most comfortable swimwear I have used in a long time. (I used to purchase suits from Swimsuits for All). I used the top and shorts for pool swimming, and the rash guard (with the top) with a pair of their leggings for ocean swimming. The leggings were comfortable in and out of the water.
The one downside is they are slow to dry and they are expensive. But they are having a sale right now if you want to try them out.
ETA: The size range runs from 12-44, which is great for people who need something larger than 26/28.