Advanced Mobility Mechanics adds new mobility mechanics to minecraft. These include:
- Climbing fences, bamboo, chains, rods, and more!
- Double jumping
- Crawling
To Double jump, jump into the air and sneak and jump again. (JUMP -> SNEAK -> JUMP) Double jumping will also negate fall damage as long as you land of the same Y-Level
To Crawl, look at a 1 block cavity (must be at your feet level and have a block above it) and then sneak and move forward.
You can also climb out of blocks such as sand and powder snow.
These features can be disabled by running /trigger amm.disable_crawling or /trigger amm.disable_double_jump.