| WALKING | In caving, a passage in which there is enough head room to walk upright. cf Flattener, Crawlway, Stooping. Cave - Parts of. Ref MM |
| WATER SINK | (Looking for a definition) Speleology term. Ref MM |
| WATER TRACING | Determination of water connection between points of stream disappearance or of soil water seepage and points of reappearance on the surface or underground. Survey & Mapping term. Ref JJ |
| WATER TRAP | A place where a cave roof dips under water but lifts above it farther on. Cf. duck (-under). Speleology term. Ref JJ |
| WATERTABLE | The surface between phreatic water which completely fills voids in the rock, and ground air, which partially fills higher voids. Speleology term. Ref JJ |
| WELL | A deep rounded hole in a cave floor or on the surface in karst. cf Rockhole. Cave - Parts of. Ref JJ |
| WET CAVE | A cave containing a lake, often a non flowing (or extremely slow flowing) lake at water table. cf Dead cave, Dry cave. Cave - Kinds of. Ref MM |
| WET SUIT | A garment of foam neoprene that insulates a diver from the cold by allowing a thin film of water to penetrate between the suit and the body. Diving terms. Ref JJ |
| WHALETAIL | A descender consisting of an aluminium block with slots, knobs and a safety gate. Speleology term. Ref JJ |
| WHISTLE SIGNALS | In climbing, 1= Stop, 2= Up, 3= Down. The SUD acronym is used widely. 4 = OK/Safe, and 1 long blast = Help is also used. Climbing and SRT. Ref GB |
| WINDOW | An irregular opening through a thin rock wall in a cave. A similar hole that forms a cave entrance. Speleology term. Ref JJ |
| WIRE LADDER | A flexible lightweight ladder of steel wires and aluminium alloy rungs. Climbing and SRT. Ref MM |