Thousand Island Lake Backpacking (2025)

Dates: August 2-3, 2025

I recently took a few friends on their first ever backpacking trip to Thousand Island Lake, having heard so much about the lake and the views there.

We took the River Trail directly to the lake from Agnew Meadows, and returned the second day via the JMT passing Emerald, Ruby, and Garnet Lake before taking the Garnet Lake cutoff back to the river trail (didn’t get around to visiting Shadow Lake unfortunately). We had fair weather the entire weekend, without a single cloud in the sky.

Day 1: Agnew Meadows to Thousand Island Lake via River Trail (9 miles, +2000 ft elevation gain)

We had to take the shuttle from the Mammoth Adventure center to the first stop, Agnew Meadows. The shuttle is very convenient to take on the way in; just buy a ticket at the Adventure center and get on the shuttle, which runs every 20 minutes for most of the day during the weekends.

Water sources were readily available along the River Trail and we didn’t need to carry more than a liter at a time. The elevation gain was pretty well distributed along the whole distance, and there was no part that was significantly difficult. The trail was a little sandy for the first few miles, which was a little annoying to walk along since each step kicked up a good amount of dust. We had regular breaks along the trail, taking in the sights and eating our snacks. When we finally crested the hill and turned toward the outlet of the Thousand Island Lake, we were greeted with the view of Banner Peak rising into view over the trees. It took us some time to find a good place to camp along the shore since we didn’t want to be too far from the water and many places were marked for restoration. There were a decent number of people camped here for the night, which is not surprising given its popularity and intersection with the JMT and PCT. (Turns out more sandy sites were higher up along the shore than I expected.) For dinner, we brought along burritos that we bought in Mammoth right before we got on the shuttle. Not the greatest burrito in the world, but it was still slightly warm and delicious after a long hike.

Approaching the lake.

The view of Banner Peak and the Thousand Island Lake exceeded my expectations. The changing sunlight during sunset and sunrise created a beautiful warm glow on the peak that faded into the night; however, the night was not any more incredible under the light of the stars and moon. I woke up several times at night to capture photos of the Milky Way rising over Banner Peak, reflected in the still water of the night. It was nearly silent after the wind died down past sunset, with only the occasional blip of noise from nearby animals.

Perfect reflection.

Day 2: Thousand Island Lake to Agnew Meadows via JMT, Garnet Lake Cutoff (10 miles, +800 ft elevation gain)

We woke up to the numbing feeling of the cold morning air on our faces; it got a bit colder than I had anticipated but not unusual for the elevation. There was frost on the plants and parts of our tent, and we could see fog rising off of the water as the sun rose to warm up the landscape. We were in no rush to leave camp, and took our time warming up with cups of hot tea and rehydrated breakfast meals. Since we got to camp just before sunset yesterday and I didn’t have enough time to paint, I did a painting of Banner Peak in the morning before we headed out for the day. I wish I could have gotten a painting during the sunrise itself to try to capture the red and orange glow, but it was either photos or the painting. It was also probably too cold for me to enjoy painting first thing in the morning. We got started hiking just before 10 AM, with the heat of the sun in full effect.

Fog over the water.

Frost-covered grass catching the morning light.

Hard to open the frosted bear canister.

We crossed the stream at the output of Thousand Island Lake, and went slightly uphill to pass the Emerald and Ruby lakes before descending to Garnet Lake. Here, we took a longer break to jump back into the water and cool off before finishing off the last five miles of the hike. To spare us from having to climb uphill more, we took the Garnet Lake cutoff trail which beelines right back to the River Trail. The cutoff on the return route is relatively unmaintained, as the sign at the top states. You first hike down on large talus before getting back to dirt, and it is decently steep but nothing crazy. From here, it was just a steady grind back to Agnew Meadows.

The hike back was not much easier than yesterday for my friends; the thinner air at elevation was taking its toll on our endurance and the fatigue from yesterday was not helping despite today being much more downhill. Their backpack fit also didn’t seem to be perfectly dialed in yet, so their shoulders were quite sore. I won't lie, in hindsight this was a slightly ambitious first backpacking trip but nothing I didn't think they could do. I appreciated Kevin and Andy's company (definitely more fun that if I did this alone), and hope they'll be back for more trips.

The return shuttle from the trailhead back to Mammoth was a little scuffed since we could not take the shuttle heading directly back to Mammoth after it completed the loop (it was full of people returning). We had to ride the shuttle in the outbound direction around the whole loop before going back to Mammoth for there to be room for us. 

All in all, a successful but tiring outing. If we were able to stay closer to Mammoth the night before, it would have made the first day much more relaxing and given us time to lounge at camp instead of the hike being a time crunch. If you want to recreate this trip, I've read online that you should take the High Trail (if you can get permits for it) so you have better views on the way in and out at the expense of being more exposed and not having water along the trail. We deleted some tri-tip sandwiches and milkshakes from the Mammoth Smoke Shack before starting the long drive back home to the Bay Area.