- Iceland
- Ice-formation-decorated chamber beyond the Crystal Maze, most readily
accessible via 161e and Roast Beef, or via Bounce Rift at furthest point of
Puerile Humour Series (1996)
- Ignorance is Bliss
- 2nd pitch of Ignore this Bit (1993)
- Ignore This Bit
- Passage off from ledge part way down Automatic Doors (1993)
- Indian Rope Trick
- 7m climb up from below The Thirty in Drunk and Stupid (1989) to
[C1989-161-09]
- Indian Scoop
- In short
horizontal passage just before Dreaming Pitch in Dreamtime (1989)
- Infinite Improbability
Drive
- Superb phreatic tube reached from Biscuit Factory via Vogon
Constructor Ship, leading to Skeleton in the Cupboard (1994)
- Interview Blues
- Deep
Vertical Series (to -451m) from Trifurcation at end of Triassic Park (1996)
named for initial explorer who had to return to UK for an interview after
just one trip