Big Falls is located across Kyle Canyon from the far more popular Mary Jane Falls hike and is without question an even more spectacular waterfall than Mary Jane. Nevertheless, this hike remains off the beaten path—not to mention the Spring Mountains visitor maps.
Follow the Mary Jane Falls Trail from the parking area to the beginning of the switchbacks. The hike to Big Falls leaves the trail and continues up-canyon before veering left to walk up a wash that may or may not have a visible trail, depending on recent storm and flooding activity and the length of time hikers have had to carve out a new course. There may be cairns here showing the right direction; however, what you're aiming for is another canyon wash that intersects with the left side of the Kyle Canyon wash. Upon finding this smaller wash, head across it and find the path leading from it on the opposite bank.
This route is prone to landslides and high flows that bury portions of the trail, and as the canyon proceeds, it becomes increasingly narrow, meaning that at some point jumping boulders up the canyon bottom will become the easiest and most direct route to the falls. A smaller boulder-obstructed slot in the canyon requires either climbing a rope to continue up the canyon bottom or scrambling up the steep banks of the canyon to bypass it.
Big Falls has a seasonal flow. Snow remains on the ground in this shady canyon much later than most other parts of the Spring Mountains. Aim to hike the falls before flows trickle off in the warmer months but after slick, icy patches of snow near the top of the hike melt away.
The dirt is loose, the rocks are slick, the trail is unclear, and the air is thin. However, those who are able to make it past all of this are rewarded with Big Falls, an 85-foot waterfall—probably the most visually arresting in the Spring Mountains—that flows off of Mount Charleston's limestone rock face into a pool at its base.
Enjoy it, catch your breath, and let your legs settle down after the climb. If it's warm enough, stand beneath it. When you're ready, turn around and retrace your route back down—it will be significantly easier than the way up!