This is what I'm looking for:
TLDR: A kind of Google Map, but with our own images. And instead of using 1 very, very big image of our virtual world, we'd only have images of part that arent water.
I really want it like the Second Life map. I managed to make it myself with 1 big image that is cut into tiles, but that's too heavy.
Because our world can be like 90000 px X 90000 px (approximatly)
so making that huge image is too heavy
The point is that almost all the map is water, so it doesnt have to be a rendered image. It can be simply a css color for the background, where there's no image.