I am down on my knees pumping from a silty puddle, praying I can get one lousy liter—we’ll need that and more to reach what I’ve heard is the best 10 miles in the entire Grand. The previous night my friend, Jane, and I made a waterless camp at the junction of the South Bass and West Tonto Trails, five miles from the South Bass trailhead. We planned, or more accurately, hoped, to top off here in Serpentine Canyon.

Located in the remote western end of the park and snaking into the deep side canyons of the Tonto Plateau, the Jewels Route is, in total, a 48-mile prize I’d been lusting after for years. These inaccessible spots—each named for a precious gem (Ruby, Turquoise, Sapphire, Agate)—are legendary for their seasonal grottoes and solitude, even though the Park Service does its best to discourage visitors. “There are no permanent springs,” warns the NPS website. “Only unreliable, unpredictable seasonal trickles.” Plus, there are no bailouts, prompting the park to dub the stretch from South Bass to Boucher Trail the most difficult section of the trans-canyon trail system.

At least 10 hikers have died here in the last 50 years by making the same mistake we might be. But we roll the dice—seems a reasonable gamble since we are here after a very wet winter. So with three liters between us, we clamber up the trailless scree slope of Serpentine and search for a cairn on the blinding-bright expanse of the Tonto.

Our boots crunch on a fine pavement of gray-green Bright Angel shale as we weave our way through a sea of blackbrush. The hulking orange Havasupai Point rises against the South Rim while the distant white spine of the Sagitarius Ridge defines the North Rim. Perched halfway between the top of the rim and the river, the Tonto Plateau is a balcony with best-seat-in-the-house views of the canyon. Periodically, we venture to the edge and peer 2,000 feet straight down to the blue-green Colorado.

We arrive at the lip of Ruby Canyon with barely a half-liter. The sun is unrelenting, and my head throbs. We look into the dark, seemingly bottomless drainage. We hear a pattering, like light rockfall, echoing off the canyon walls. Sheep? We cock our heads: water gurgling over slickrock!

Our timing is perfect; the seasonal springs in Ruby are ripe with snowmelt and feeding a lush, riparian oasis. A string of clear pools glint in the sunlight. Damselflies hover and zag. Bright green ferns, moss, and monkey flower pad the canyon walls.

The next day, after lounging in Ruby all morning, we confidently march across the parched Tonto for 5.8 miles to Turquoise Canyon, our next camp, where another perfect oasis awaits. You can continue on the Tonto to Hermit trailhead or turn back and just bag these 10 miles. Or stay another day. No matter what, you win.

—Annette McGivney

PERFECT 10 MILES Tonto Trail from Serpentine Canyon to Turquoise Canyon

SEASON The only reliable water is Boucher Creek; seasonal flows run in Ruby, Turquoise, Sapphire, and Slate. Best bet for water and reasonable temperatures: February-April.

CAMPSITES Side canyons, such as Ruby, Turquoise, and Sapphire Canyons are good places to set up camp; you may find seasonal water here, too.

MAPS USGS quads Grand Canyon, Piute Point, Shiva Temple, and Havasupai Point ($8 each, store.usgs.gov)

PERMIT Required. Book four months in advance.

CONTACT (928) 638-7875; nps.gov/grca