You can make yourself light enough to walk without your weight triggering traps or even on water.

Prerequisite(s): Dex 16, ki pool class feature, 9th-level monk

Benefit: Because of your ki pool, you no longer trigger traps and hazards that are activated by weight. So long as you are moving at least 5' per round, the surface you are walking on considers you weightless. You may walk across snow without breaking the crust, trapdoors without falling and even water of any depth. If you do not move for one full round, your weight has its full impact where you stand with all appropriate implications.

As long as there is at least 1 point in his ki pool, you can make use of this feat.