Skylight Cave is a lava tube formed during an eruption of nearby Sixmile Butte. As the lava cooled, the surface hardened into a crust while still-molten rock continued to drain underneath, leaving behind a hollow tube about 1,017 feet long. In a few places along that tube, the lava had built small chimneys called hornitos on the ceiling. Those hornitos eventually collapsed, opening three vertical shafts to the surface and creating the cave’s namesake skylights.

One of those collapses, larger than the others, became the entrance. From the surface it looks like a hole in the ground next to a Forest Service sign. From inside, with the rest of the tube stretching out in two directions, it’s the only way down.

The cave is in the Deschutes National Forest, about 9 miles northwest of Sisters. From outside the entrance, on a clear day, you can see Mount Washington, Three Fingered Jack, and Black Butte. The volcanic landscape that made this cave is also the landscape you’re standing on top of.

The cave is open May 1 through September 14. The Forest Service closes it from September 15 through April 30 to protect a colony of hibernating Townsend’s big-eared bats. The steel ladder is sometimes removed during the closure, so attempting access in the off-season is both prohibited and physically difficult.

The beams need direct sunlight to form. On overcast days, even in the middle of the open season, the cave is just a quiet, dim lava tube. Check the forecast for Sisters before you commit to the drive in.

Why the timing is so narrow

Each skylight is a roughly vertical shaft a few feet across. For sunlight to make it all the way through to the cave floor, the sun has to be at a steep enough angle to shine straight down the shaft. That only happens for a couple of hours each morning during the months when the sun arcs high overhead. Outside that window, the sun hits the side of the shaft instead of the bottom, and you get diffuse light at best.

The hardest part of visiting Skylight Cave is the drive. The roads are not dangerous, but there are a lot of unmarked Forest Service spurs out there, and Google Maps has been known to send people down dead ends. Use the directions below in addition to your phone’s navigation, not instead of it.

What kind of vehicle you need

Most low-clearance 2WD cars make it in dry conditions if you take the gravel slowly. After rain or in early season, ruts and washboard sections can scrape an undercarriage, so a high-clearance SUV or truck is the smarter choice. Total drive time from Sisters is roughly 30 minutes; from Bend, plan an hour.

The Forest Service has set aside a small wide spot in the road as the parking area, marked with a sign that reads “Please Park Here.” It fits maybe four or five cars. Don’t park at the cave entrance itself. That’s a single-lane Forest Service road and blocking it isn’t allowed.

From the parking turnoff, walk back along the road in the same direction you were driving. The cave entrance is about 0.15 miles further on the right, marked by a Forest Service sign with bat protection notices and a visitor log. Sign the log. The Forest Service uses it to track use, which feeds into how the cave gets managed.

The cave is entered through a collapsed roof section roughly 10 to 15 feet deep. A steel ladder is bolted into place during the open season, with handholds at the top so you can swing down without committing immediately. Some years the ladder is replaced by a makeshift stack of log rungs, especially early in the season before the Forest Service crews get to it. If that’s what’s there, it’s fine, just slower.

There’s a small drop-off near the top of the ladder, so step carefully as you transition from the surface to the rungs. Once you’re on the ladder, the descent is straightforward. Aim to have your headlamp on your head (not in your hand) before you start climbing down; you want both hands on the ladder.

From the bottom of the ladder, the lava tube extends in two directions. The eastern passage, to your left as you face away from the ladder, contains the three skylights and dead-ends after a few hundred feet of mostly clean passage. The western passage, to your right, runs about 900 feet and is harder going: sand, clay, and breakdown piles fill much of it, and it eventually pinches out without any skylights.

Almost everyone is here for the eastern passage. From the ladder, you’ll see daylight ahead of you within a few steps; the first skylight is roughly 200 feet in, and the main chamber where all three beams land is around 300 feet in.

What it looks like once you’re there

The skylight chamber feels bigger than the cave actually is. The ceiling rises to maybe 15 feet, the walls open out, and three discrete columns of light land on the rocky floor about a body’s-length apart from each other. The dust suspended in the cave air makes the columns visible as solid shafts rather than just bright spots on the ground. They move slowly as the earth turns (a foot or two over the course of an hour) and they fade in and out as drifting clouds pass over the skylights above.

The floor is rough lava: loose, sharp, and uneven. Watch your footing, watch your head where the ceiling drops, and don’t try to scramble up to the skylights themselves. They’re delicate, and the rock around them is even sharper than the rock below.

The Forest Service’s caving recommendation for any Deschutes lava tube is three sources of light per person plus extra batteries. That’s the standard for a reason: a single flashlight failure in a cave is a problem, two failures is a serious problem, and three failures while you’re alone underground is how rescues start. Skylight Cave is short enough that the actual risk is limited, but the rule still applies.

Skylight Cave is closed for more than half the year because Townsend’s big-eared bats hibernate inside it. Townsend’s are listed as a sensitive species in Oregon, and disturbing them during hibernation costs energy they cannot replace until spring. That’s why the September 15 to April 30 closure is hard, not advisory.

The other major bat issue is white-nose syndrome, a fungal disease (Pseudogymnoascus destructans) that has killed millions of North American bats since 2006. The fungus survives on clothing, footwear, and gear that has been in contact with infected caves, and humans are one of its main vectors between cave systems. The Pacific Northwest is on the leading edge of the disease’s spread west.

The thing that makes the beams visible to your eyes, fine dust suspended in the cave air, is also the thing that makes them photographable. A camera in low light pointed at the chamber wall sees almost nothing; pointed at one of the columns it sees the same shaft you see. The challenge is the contrast: the beam is bright, the surrounding rock is very dark, and most cameras can’t hold both at once.

Settings that work

• Camera: A mirrorless or DSLR with a wide-aperture lens (f/2.8 or wider) handles this much better than a phone. Phones can capture the beams, but the dynamic range will fight you.
• Aperture: Wide open or near-wide (f/2.8–f/4) to keep ISO down.
• ISO: Start at 800 and adjust. The beam itself is bright enough that 1600 is rarely necessary if you can stabilize.
• Shutter: 1/30s to 1/4s on a tripod, depending on how dramatic you want the dust to look. Longer shutters smooth the dust into a glow; shorter shutters preserve texture.
• White balance: Daylight or 5500K. The beams are direct sunlight; auto white balance often pulls them too warm.

Bring a microfiber cloth (the cave is dusty enough that lens fronts pick up grit fast), and don’t change lenses inside the cave if you can avoid it. If you want a person in the shot, place them at the edge of one of the beams rather than directly in it; standing in the column itself blocks the visible part of the light.

You’ll be out of the cave by 10:30 a.m. or so on most visits, which is early enough to make a real day of the surrounding area. A few of the obvious options:

Black Butte Ranch · Lakeside Bistro

The closest sit-down lunch is the Black Butte Ranch Lakeside Bistro, with indoor and dog-friendly outdoor seating overlooking Phalarope Lake. The view across the water lines up the Three Sisters, Mount Washington, and Mount Jefferson on a clear day. Coffee, wine, baked goods, and a small gift shop are also on site.

Other Central Oregon caves

If you’ve come this far for one lava tube, two more in the area are worth pairing with it. The Lava River Cave at Newberry National Volcanic Monument is the longest continuous lava tube in Oregon at just over a mile and requires a timed reservation in summer. Boyd Cave, near Bend, is open year-round and has no fee. Decontaminate between visits.

Sisters and the Metolius corridor

The town of Sisters itself is 30 minutes back. From there you can extend the day with a stop at Camp Sherman on the Metolius River, the Suttle Lake loop, or the drive up to the McKenzie Pass summit at the Dee Wright Observatory (Highway 242, open seasonally July through October).