Worth noting, if you are leviathan hunting but still avoiding serpents until you actually get that harpoon, explore ocean biomes during sunny days. Serpents spawn at night and/or during storms, so sunny days are perfectly fine (note that night spawns disappear at day, but daytime storm spawns will stick around their spawn area indefinitely until murdered)...and honestly it's not always great to try and moor your ship next to a leviathan in a storm, especially at night. It does have collision and waves are already known to beat up your boat a bit, especially when the goal is to park as close as possible to it.