Its four perennial streams support steelhead and coho salmon, and its wetlands are habitat to the rare San Francisco garter snake and California red-legged frog.

Cultural resources include the remnants of a prehistoric Native American village site and a number of structures from the 19th century Cascade Ranch.

In conjunction with adjacent and nearby public lands, the unit permits the protection of important regional ecological corridors.

Franciscan missionary Juan Crespi noted in his diary, "We...halted on a steep rock, in sight of the point which we judged to be Año Nuevo, on the bank of an arroyo which empties into the sea.

Año Nuevo State Park is the site of one of the largest mainland breeding colonies for the northern elephant seal (another is in Piedras Blancas State Marine Reserve and Marine Conservation Area—100 miles (161 km) south near the town of Cambria and the San Simeon approach to Hearst Castle).

The elephant seals return to Año Nuevo's beaches during the spring (females) and summer (males) months to molt, and can be observed during this time through a permit system.

[8] A Visitor Center features natural history exhibits and a bookstore offering educational items such as books, postcards and posters.

[9] The former Cascade Ranch unit of the reserve includes steep unmarked hikes in the coastal hills inland of the highway.