Alter Aeon Online Help

Keywords are:  'skill survivalist spelunking caving caveing'

Skill: spelunking               Lvl 18  Any  (85%)
                                Requires: climbing
                                Group: Orienteering
                                Guild: The Cartographers Guild  Rank: Adept

'spelunking' is an automatic skill that works when underground, primarily
in caves.  A player with this skill may be able to go places that others
cannot, and will generally be able to proceed more quickly and without
getting tired as quickly. It also becomes less tiring to gather raw
materials in subterranean areas when well-versed in the skill.

If you know spelunking, you will be slightly more effective when hiding
in subterranean terrains.