Our longest hike to date was upon us – a 17 mile monster to the rarely visited Frigid Lake, nestled below the continental divide at 11,820 feet. The excursion required 1.8 miles of off-trail travel from Thunder Lake. This included bushwhacking, boulder hopping and a good deal of route finding. Thunder Lake, Box Lake, Eagle Lake, Indigo Pond and Mertensia Falls rounded out our agenda for the day.
Video of our Hike to Frigid, Eagle, Box, Thunder Lakes, and Mertensia falls
The goal was to reach Thunder Lake for a 6:50AM sunrise, which meant hiking 6.2 miles by headlamp. We estimated it would take between 2 and 3 hours. Thus we found ourselves at the Wild Basin Trailhead at 4:15. We made the trip to Estes Park the day prior to stay in the KOA, but I forgot the tent poles. Luckily we were able to grab a last minute hotel room – we were closer to the trailhead and did not have to spend extra time in the morning deconstructing camp.
This distance hiking in the dark is only surpassed by our Longs Peak summit mid-August. We made excellent time by taking the Thunder Lake Trail through the wilderness campsites. 2,000 feet of elevation is spread evenly between the trailhead and Thunder Lake, creating a moderate hike through the forest along North St. Vrain Creek.
A Sunrise at Thunder Lake
With a little urgency, we were able to make it to the banks of Thunder Lake just as the sun was rising. We were hoping for some colorful aspens circling the lake, but as it happens we only got an eyeful of pines. The alpenglow on Mount Alice and Pilot Mountain to the northwest more than accommodated for the lack of aspens.
Across the lake is a silvery cascade rounding out the scenery. Fan Falls, a destination I’m sure we’ll visit someday. There was a tent set up close to the water but otherwise we had the lake to ourselves. The weather was predicted to be warm for the day, but we found ourselves shivering and throwing on extra layers at Thunder Lake.
Now that the sun was out, all three GoPros (Dave splurged on the GoPro 9), camera and tripod were unpacked to capture footage and landscape photography. In order to attain Box and Eagle Lakes, cross the Thunder Lake drainage using a faint path that curls to the left. The trail to these lakes is not recognized by the park, but it’s easy to navigate the 1.3 miles to Box Lake.
The vertical distance between Thunder and Box Lakes is a scant 100 feet, but the path requires a drop of 150 feet to avoid climbing up the rocky slopes of Tanima Peak on the right, followed by a considerable gain. Word to the wise – do not put too much trust in cairns; we followed two on this section incorrectly and got off trail. Maps and route finding skills are much more useful. While on this trail, take shoulder checks for excellent views of Longs Peak and Mount Meeker.
Box Lake was a Beauty
Other than a few angular corners, this little beauty does not bear a resemblance to a box. Surrounded by rocks and stunted trees, Box Lake sits at 10,740 feet at the base of Tanima Peak. We hopped along brown colored rocks to get some shots by the water’s edge before turning sharply left up a steep slope toward Eagle Lake.
Between Eagle and Box Lakes the dispersed cairns were accurate and helpful when route finding. A faint trail persists through the two destinations, winding past an unnamed pond. We stopped to admire the pond and soon after we were greeted with the long finger of Eagle Lake.
A Nice Bushwhack to Eagle Lake
Box Lake is miniature in comparison to Eagle Lake, situated at 10,820 feet and rimmed by Mahana Peak and Tanima Peak.
Here we got a first glimpse of Eagles Beak, a curious formation jutting over the basin holding Eagle Lake. Two unnamed waterfalls framing the lake add to the splendor.
In order to reach Frigid Lake, we headed south toward the headwaters of Eagle Lake. The banks are choked with stunted trees – the best route involves hopping over rocks close to the water’s edge. Eagle Lake is 0.3 miles in total length and we spent a good deal of time navigating around it. Despite the distance, we were rewarded with various photographic viewpoints of Eagle Lake as we walked. The edges of Eagle Lake are beach-like and sandy for several feet before a sudden drop-off, creating a pleasing color scheme.
Finding the rarely visited, Frigid Lake
A small creek originating from Indigo Pond marked our deviation from colorful Eagle Lake. We began walking through a relatively flat meadow along the creek, which eventually gave way to a boulder field. A dried up pond and a fork in the creek indicated our left-hand turn to Frigid Lake. Our path differed from the one in the guide; we reckoned it would be easier for navigation to use the creek as our landmark. The upward path of the creek, however, turned out to be trickier than expected.
The 0.8 miles and 900 feet of elevation gain from the withered pond to Frigid Lake is predominantly boulder hopping with no path. The creek we climbed alongside is charming, but at times it made our ascent slippery. Not ideal conditions for our position on the rocks. Eagle Lake and two unnamed ponds to the right served as an exquisite background behind us, while Eagles Beak remained a constant incentive to continue on.
Frigid Lake and Moomaw Glacier
Arduous as the ascent was, we thrilled at the sight of Frigid Lake. A short boulder descent placed us at the water. Across the lake, massive Moomaw Glacier clung to the slopes – still boasting a sizeable amount of snow this late in the season; I am curious to know if it’s ever melted entirely. The glacier hung over the water in a peculiar way, as if huge chunks had previously cleaved off (in fact, I saw one big snowball detach from the glacier and make a grand splash in the water).
The most impressive configuration highlighting Frigid Lake is Eagles Beak. The craggy rock spire rises on the right side of the lake, standing between us and Indigo Pond. Our mileage one way totaled 9.4 miles so far; our aspirations of achieving Indigo Pond today was out of the question, especially with Mertensia Falls in our future.
On the descent, we skirted the slippery waterfall and hung closer to a snowfield. I am unsure if our path down was any less dangerous than the one we took up. Clouds raced across the sky and we feared a thunderstorm. But there was no rain for the remainder of our trip. It’s a challenge to predict future weather at some locations in the park where ridges hide the sky – we faced a similar situation on our first attempt of Cony Lake.
Trying to find Mertensia Falls
By the time we doubled back to Eagle Lake we were ecstatic to be rid of the boulder hopping. After winding past Box Lake back into forest terrain, we searched for a waypoint to leave the trail and push toward Mertensia Falls. In the end we opted to adhere to a tributary of North St. Vrain Creek; the elevation grade was no better from any other direction.
The initial stages of our bushwhack were mild, but upon reaching the crux of two adjoining tributaries the conditions made an abrupt change. Rocks slick with creek water that rose on either side necessitated hopping over the stream a few times. The downhill slope of the rocks added to the uncertainty of the hike. There were countless cascades preceding Mertensia Falls that kept us company during our travails.
We Found Mertensia Falls
Mertensia Falls truly is a gorgeous waterfall with views of Mount Meeker and Longs Peak hovering over the trees. I would love to see this waterfall in early summer when it’s really roaring.
Getting to Mertensia Falls was only the first half of our toils; afterwards we faced an exhausting battle through the woods to rejoin the Thunder Lake Trail. Some unnamed hidden waterfalls along North St. Vrain Creek did little to comfort us as we maneuvered around fallen trees and brush. The excursion in its entirety was one mile, but it felt like much longer, particularly after our push to Frigid Lake.
After 6 miles of off-trail travel, Thunder Lake Trail in all its maintained glory was a sight for sore eyes; it was smooth sailing the remaining 5 miles to the trailhead. Our hike today brought endless solitude. We didn’t see a soul until meeting back up with a main artery in Wild Basin. Total mileage clocked in at 17 miles even. Complemented by 3,950 feet of elevation gain – our longest hike yet. Missing Indigo Pond was a disappointment, but I am looking forward to a return trip to this remote corner of Rocky Mountain National Park. Stay tuned!
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