The lowest snowfield in California that does not disappear except in the extreme runs of dry years is located above Mirror Lake at an elevation of 6,600 ft (2,000 m).

According to recent, but incorrect, USGS maps, 35 permanent bodies of snow and several tiny glaciers dotted the highest peaks of the Alps.

[5] On the ridge south of Sapphire Lake is an unusual phenomenon consisting of a temporary glacier, versus an inactive snowfield that melts out in dry years.

Following years of heavy accumulation, an icefield appears in this fully sheltered north-facing cirque that can show active crevasses and seracs some tens of feet high.

Studies of lichen collars indicate that the site near Kalmia Lake is the snowiest spot in the State of California, receiving snow accumulation in excess of the Lake Helen snowcourse on Lassen Peak, by far the snowcourse with greatest late winter snow accumulation in California.

Sufficient snow does accumulate under Brokeoff that in some years the snowfield there experiences incipient glacial motion.

The Trinity Alps section of the Klamath Mountains Ecoregion is botanically outstanding by having the second greatest number of conifer species of any place in the world.

Northern tree species, such as subalpine fir (Abies lasiocarpa), Pacific silver fir (Abies amabilis), and Engelmann spruce (Picea engelmannii) are found here, as well as southern trees, such as incense cedar (Calocedrus decurrens), ponderosa pine (Pinus ponderosa), and white fir (Abies concolor), plus unique populations of foxtail pine (Pinus balfouriana) and weeping spruce (Picea breweriana).Other plants along the trails include the carnivorous California pitcher plant (Darlingtonia californica), the showy pinkish Lewisia cotyledon, and the rare Trinity Alps endemic wildflower Trinity penstemon (Penstemon tracyi).

The Trinity Alps are home to much wildlife, including: American black bear, mountain lion, bobcat, blacktailed deer, lizards, chipmunks, and a great number of bird species.

The western ridges are mostly lower in elevation with fewer lakes, and ridgetop trails there can be hot and dry in the summer.

Rock climbing is excellent in the areas with granite cliffs, such as Caribou Peak and Sawtooth Ridge.