Minecraft wiki entry for Beach, associated text: The standard beach-type biome variant, Beaches are composed of mostly sand, with some gravel, dirt, and clay patches under the water, similarly to rivers. Like the sand in deserts, sandstone generates underneath it, preventing it from falling into caves below. Beach terrain is usually a smooth descent into the water, though it can vary in steepness and width. Turtles can spawn here, as can buried treasure, shipwrecks and rarely underwater ruins.