I got the Blessed Sea on a Large Big and Small Map / normal islands. It required settling on 13 different landmasses. It was a fun quest actually and it wound up helping me to a big win since I was running a coastal GLH economy and all those cities on tiny islands had 5 foreign trade routes by the end. Plus I got Sid's Sushi, so they all wound up at Pop 25+ For the reward, I took the GP and used it for a second Golden Age. I had sent missionaries already with the settler stack to get border pops and all of the cities that still needed temples were pop 5 and under (the newly settled island cities). But, in the end it forced me to develop my economy in a way that was much more powerful than I would have thought.