On page 20 the DSG offers this explanation, "The techniques of spelunking, or cave exploration, can be useful to any characters who have to crawl around in narrow spaces underground. Many aspects of spelunking are subsumed under other movement rules, particularly climbing, swimming, and jumping. Mapmaking is another dungeoneering skill that has obvious benefits for cave exploration."
And now for two random images to wet your spelunking senses...
True spelunking eventually leads to crawling into narrow and tight spaces. Something no sane D&D character should contemplate as in the D&D world the elements are the smallest danger.
The DSG gives rules for the TIGHT SQUEEZE
Ceiling between 2/3 and full character’s height, he can walk upright at 2/3 of his normal movement rate.
Ceiling between 1/4 - 2/3 character's height, he must crawl on hands and knees. Additionally movement rate 1/2 normal, -5 to attack rolls, lose all dexterity and shield bonuses, and don't forget to consult AD&D Weapons Table for "Space Required" to wield that weapon.
Ceilings between minimum for character to 1/4 character's height, he must slither along in a prone position. Additionally movement rate 1/4 normal, -8 to attack rolls, lose all dexterity and shield bonuses, and don't forget to consult AD&D Weapons Table for "Space Required" to wield that weapon.
And there is a table for the minimum hole a character can squeeze into modified by race and armor type.
Character Race Tunnel Width Tunnel Height
Human/dwarf 2ft 1ft (damn those dwarven shoulders)
Halfling 1ft 2/3 ft
Elf 1.5 ft 3/4ft
What no modifier for sex.
And if the DM wants to get his characters naked....
Modify the above table by
Leather = none
Chain = +1/4 ft
Plate mail = +2/3 ft
Is this all OTT (over the top), of course it is. It is the DSG.
But it should encourage the DM to make the physical world as challenging as the monsters set against the party. Or make the party fight these monsters in tight spaces, or place that treasure in a really narrow tunnel and see who goes in first.
Gems we should take
1. Spelunking rules
2. An encouragement to make the physical world a challenge in itself