The eXplorist 210 is waterproof at IPX6, the eXplorist models 100, 200, 300, 400, 500, 500LE, and 600 are waterproof at IPX7. What's the difference?
6 Protected against heavy seas. Water projected at all angles through a 12.5mm nozzle at a flow rate
of 100 liters/min at a gage pressure of 100kN/m2 for 3 minutes from a distance of 3 meters.
7 Protected against water immersion. Immersion for 30 minutes at a depth of 1 meter.
So get the 210 and save some cache as long as you don't see an immersion in it's future!