Angew Meadows to Twin Island Lakes

This stunning out-and-back route begins at Agnew Meadows in the Ansel Adams Wilderness and leads deep into the Sierra backcountry to the remote and scenic Twin Island Lakes. At 56.4 miles round-trip, this high-elevation adventure offers a mix of well-maintained trails and rugged, lesser-traveled terrain. Along the way, hikers are treated to alpine meadows, cascading creeks, iconic peaks, and shimmering lakes. This route is ideal for experienced backpackers looking for solitude, off-trail exploration, and classic Eastern Sierra beauty.

Start at Agnew Meadows, just outside of Mammoth Lakes. Take the Pacific Crest Trail (PCT) south towards Devil’s Postpile. Head west on the Mammoth Trail and take that all the way to the junction with Iron Creek Trail. Turn right on Iron Creek Trail and begin to head north. Iron Creek Trail transitions to Stevenson Trail which will take you all the way to Twin Island Lakes.

Twin Island Lakes sit at just over 10,200’, nestled beneath towering ridges and surrounded by rocky outcrops. The area is wild and quiet, offering dramatic scenery and excellent backcountry camping options. After soaking it all in, retrace your steps to return to Agnew Meadows.

Flora & Fauna
Lower elevations feature red fir, lodgepole pine, and aspen groves. As you climb, the landscape opens to subalpine meadows, granite plateaus, and high-elevation basins filled with wildflowers in early summer. Wildlife includes marmots, pikas, mule deer, and the occasional black bear. Keep food secure and follow Leave No Trace principles to protect this delicate ecosystem.

Permits
A wilderness permit is required for all overnight trips in the Ansel Adams Wilderness. Agnew Meadows trailhead is quota-controlled and can be reserved through recreation.gov. You’ll also need to carry a bear canister, which is required for food storage in this area.

Considerations

• This is a remote, strenuous backpacking route with significant mileage, elevation gain, and some route-finding near Twin Island Lakes.
   

• Mosquitoes can be intense in early season—bring a head net and repellent.
   

• Snow may linger into early summer on higher sections like Island Pass.
   

• Creek crossings can be high in early season.
   

• Twin Island Lakes area is remote with no established campsites—choose durable surfaces and minimize impact.
   

• Prepare for sudden weather changes and bring proper navigation tools.