Design a large 512 x 512 underwater...

Design a large 512 x 512 underwater landscape as the main subject. The scene should be a detailed ocean floor with uneven terrain, including sand, rocks, coral, and natural formations. Add strong height variation with slopes, dips, and layered ground to create depth. Include parts of a giant octopus within the environment, such as tentacles extending across the seabed and partially buried or wrapped around terrain. Do not generate a full standalone octopus. The creature should only appear as a secondary element integrated into the environment. Focus on a wide, immersive underwater scene.