Create one Fire-to-Water transition...

Create one Fire-to-Water transition landmark on the 128 grid, about 65 blocks wide: ancient steam-bath ruins with three sealed shallow pools, broken arched colonnades, a vaulted bath chamber, walkable steps, and vents where contained heat meets water. Transition materials gradually: basalt, blackstone, and magma on one side; pale stone, prismarine, and moss on the other, with tuff and weathered stone in the center. Add chimney vents, cracked paving, reeds, and small cascades. Keep pool floors complete and all paths safe. Include only a compact site. No volcano or ocean.