Scanning a Reaper in Subnautica in Survival Mode is bragging rights. These creatures are the 3rd largest agressive Fauna, anyway. These pains in the butt can be found in vast areas such as the Dunes and the Crash Zone. Scanning one in Creative is nothing to brag about, obviously. Their 4 large mandibles allow them to trap prey and are useful for attacking a wide variety of different creatures. This description plus the image on the front cover would give a 4-year-old nightmares!

If you do want to scan a Reaper Leviathan, however, then pack an Oxygen Tank, a Stasis Rifle, a Reinforced Dive Suit and Reinforced Gloves, a Thermoblade, and of course your Scanner. Optional: Propulsion Cannon, Repulsion Cannon