Reapers are the scariest for sure. It’s not really their appearance, but the biomes they appear in. They appear out of nowhere in the murky waters. I never had to encounter a ghost in outside of the lost river, but the color of the biome makes them less scary. The seamoth can outrun it anyway. The sea dragon always looks like it’s smiling. Besides that, a grapple hook prawn suit using the flinging strategy can zoom past them no problem.