The highest point of the range is the southern summit of the mile-long Animas Peak massif, 8,565 feet (2,611 m).

The compact southern part, which includes Animas Peak, is higher and wider, rising up to 4,000 ft (1,200 m) above the nearby valleys.

[3] The longer, narrow northern portion is lower, reaching only 7,310 ft (2,230 m) at Gillespie Peak, and is characterized by grassland and piñon-juniper woods and shrubs.

The 321,000 acre (1,299 km2) ranch (more than one third the size of the state of Rhode Island - 3140 km2) was bought in 1990 by The Nature Conservancy, which took the unusual step of selling it in the mid-1990s to the Animas Foundation, a private organization founded by poet and rancher Drummond Hadley[4] and funded in part by the Anheuser-Busch family.

Access to the ranch, and hence to portions of the Animas Mountains, is tightly controlled, with little or no public recreational use opportunities.