You've only ever seen photographs of one planet with oceans and landmasses, and that's Earth. The only other celestial body that has a solid surface with liquid on it that we've taken pictures of is Saturn's moon Titan. Titan has a thick opaque atmosphere so we don't have true-to-life pictures of the surface from space. We've got images constructed from radar scans, and this amazing image taken from the surface by the Huygens probe that hitched a ride with Cassini. The hydrocarbon lakes of Titan look like...blobs on a circle.

Every other planetary surface you've seen is rocky dirt, icy dirt, straight-up ice, cratery dirt, or opaque gas clouds. Any "earth-like" planet you've ever seen is a fictional artist's conception. And ain't no human artist who knows shit about plate tectonics compared to the Earth herself, so they draw weird shit that ain't quite right somehow.