Found this last week while messing around on new maps, showing a friend the latest update and it's features. The entire map is an ocean, except for the large island you spawn on (if you don't, the co-ords are x777, z-267). There is one miniature land mass near the edge of the map somewhere (if I remember correctly), though it's too small to be inhabitable (if you're planning a pirate themed map, it'd be perfect for a hidden treasure chest).
The map features a few patches of both roses and yellow flowers, as well as half a dozen stalks of sugar cane spread over the place. It has 6 trees, enough to get started and also guarantee you won't need to cheat in some saplings. In some of the caves it also has exposed iron and coal to help get you started. There is a small cave system underneath, though I haven't explored enough so I can't comment on the amount of diamonds or other interesting finds (that would also ruin the fun in exploring!). From what I saw, there was minimal tall grass on the island - apart from the small patch near the southern end (I think). However with the skeleton cage nearby it won't be hard to bonemeal some grass back to get seeds.
The friend I showed this map to whilst I was showing him the update, went on to LAN a 5-player game where they built a huge network of tunnels and caves in the large natural cove. I could picture a lot of places on this map to build a pirate themed base around.
Seed is: -3711951296344799968 (No idea how I initially forgot to mention this, lmao)
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