A pneumatic speargun designed for underwater combat in GLMZ's flooded infrastructure, submerged transit tunnels, and coastal industrial zones. The UW-5 fires a 30-centimeter steel spear using compressed air at velocities effective to 15 meters underwater — dramatically reduced from surface weapon ranges due to water resistance, but sufficient for the close-quarters engagements that underwater environments demand. The spear is tethered to the weapon by a retractable monofilament line, allowing recovery and reload.

Ouroboros developed the UW-5 because GLMZ has an underwater problem. Decades of subsidence, flooding, and rising water tables have created an extensive network of partially or fully submerged spaces beneath the city — old transit tunnels, basement levels, industrial chambers, and infrastructure corridors that are now accessible only by diving. These spaces are used for smuggling, storage, clandestine manufacturing, and hiding. Conventional firearms are useless underwater; the UW-5 fills the gap.

The weapon's most common deployment is during drainage operations, where security teams must clear flooded spaces that may contain hostile occupants. The UW-5's monofilament tether serves double duty — the spear can be used to anchor to structures for movement in current, and the retraction mechanism provides a crude grappling capability. In the dark, flooded tunnels beneath GLMZ, the UW-5 is the difference between an operator and a drowning victim.