Page Type: Mountain/Rock
Lat/Lon: 40.34232°N / 105.69358°W
County: Larimer
Activities: Hiking
Season: Summer
Elevation: 10640 ft / 3243 m


From Spruce LakeGabletop Mountain and Castle Rock from Spruce Lake
Castle Rock is located at the terminus of Gabletop Mountain's NE ridge and is perpendicular to 'Primrose Pond.' Castle Rock dominates the view from Spruce Lake, and receives little attention from hikers, perhaps as they might perceive it as being a technical climb. On the contrary, Castle Rock can be hastily summited in less than 30 minutes from Primrose Pond. Good route-finding skills are appropriate in order to spare yourself arduous bushwhacking and cliffing-out, but Castle Rock is a glorius place to visit and sign the register.

Elevation: 10640'+ (As specified by Lisa Foster, I got 10627' on my GPS)
Elevation Gain: 2490' (Fern Lake TH)
Mileage:5.7 Miles (Fern Lake TH)

Latitude: N40 20.570
Longitude: W105 41.512

Reaching Castle Rock

In order to summit Castle Rock one must know the way to Primrose Pond, not just Spruce Lake! From the Spruce Lake Trail Intersection .1 miles North of Fern Lake, hike approximately 1 mile to Spruce Lake. The trail is unmaintained so try your best to built appropriately sized cairns and walk on the edges of the trail to expand it. Castle Rock along with Gabletop Mountain are the most prominent landmarks to the west of Spruce Lake. Walk around the north shore of Spruce Lake following social trails to the inlet stream. A small trail, again unmaintained, leads to Primrose Pond. This trail is a great route if you can locate it, but if not, just stick to the north of the creek and follow it to the outlet of the shallow pond. From the north side of Primrose Pond, climb in a general NW direction to somewhere on the connecting ridge, NOT THE BASE OF THE ROCK. The 400' ascent to the ridgeline can be accomplished in two ways, the 'tree choked gully' as Lisa Foster describes in her book, or my way; up a rock slide consisting of beachball sized rocks. I cant make this descision for you, but I would suggest my way if you like mimimal bushwhacking. Hike north of Primrose's outlet into a stand of dead Limber pines, while looking for the rockslide that reaches to the top of the ridge. My descision to climb the rock slide was influenced by a cairn route, so keep your eyes peeled. The rock slide is actually rather stable, and few rocks shifted on me coming up or on my descent, but be aware that a snapped ankle in the area would become a major problem, as the area above Spurce Lake isn't brimming with people. At the top of the ridge, head east through sparse Limber pines, avoiding as many gendarmes as possible. After scaling these slabs, locate the obvious summit area at the end of the ridge and step across a deep crack about a foot wide to the top.

Upon your return to Primrose Pond i suggest taking the time to visit Loomis Lake just a quarter mile west before returning to Fern Lake.

If you were only going to look at one picture...

My ascent of Castle RockBlue is the unmaintained trail to Spruce Lake Yellow is the approximate route to Primrose pond Orange is my route to Castle Rock From Gabletop Mountain

Getting There

Fern Lake TH, the only feasable TH to use can be reached by exiting the Bear Lake road at Moraine Park and following the road to the TH. As snow falls in Moraine park, the final strech of the road to the TH will close at the bus stop, adding around .7 miles to your trip.

Red Tape

Park Regulations and Entrance fees apply no matter how you plan to climb Castle Rock. Visit the parks website at for more details.

Be advised to start early as afternoon thunderstorms are ALWAYS a danger.

Also, no technical gear is required to reach the summit, though there are routes directly up the rock that do require technical equiptment.


The nearest campgrounds to castle Rock are Moraine Park Campground and Glacier Basin Campground. The nearest Backcountry campsites are at Spruce Lake, Fern lake and Odessa Lake. All are stoves only.

External Links

The ProTrails overview of the route to Primrose Pond (the 'scenic pond')