Eleven miles north of Florence, you can descend into the world’s largest sea cave to observe the only U.S. mainland rookery of Steller sea lions (Eumetopias jubatus). Sea Lion Caves (91560 U.S. 101, 541/547-3111, www.sealioncaves.com, 9 a.m.–7 p.m. daily, closed Thanksgiving and Christmas, $11 adults, $10 seniors, $7 ages 3–12, children 2 and under free) is home to a herd that averages 200 individuals, although the numbers change from season to season. These animals occupy the cave during the fall and winter, which are thus the prime visitation times.

The Steller sea lions you’ll see at those times are cows, yearlings, and immature bulls. In spring and summer, they breed and raise their young on the rock ledges just outside the cave. In addition, California sea lions (Zalophus californianus), common all along the Pacific Coast, are found at Sea Lion Caves from late fall to early spring.

Enter Sea Lion Caves through the gift shop on U.S. 101. A steep downhill walk reveals stunning perspectives of the coastal cliffs as well as several kinds of gulls and cormorants that nest here. The final leg of the descent is by an elevator that drops an additional 208 feet. After stepping off the lift into the cave, your eyes adjust to the gloomy subterranean light, and you’ll see sea lions on the rock shelves amid the surging water inside the enormous cave.

Flash photography is forbidden, so study your camera’s settings if you want to take pictures inside. You have a better chance of seeing these animals inside during fall and winter. A set of stairs leads up to a view of Heceta Head Lighthouse through an opening in the cave.

Steller sea lions were referred to as lobos marinos (sea wolves) in early Spanish mariners’ accounts of their 16th-century West Coast voyages, and their doglike yelps might explain why. You’ll notice several shades of color in the herd, which has to do with the progressive lightening of their coats with age. Males sometimes weigh more than a ton and dominate the scene with macho posturings to scare off rivals for harems of as many as two dozen cows.

Their protection as an endangered species enrages many commercial anglers, who claim that the sea lions take a significant bite out of fishing revenues by preying on salmon. In any case, the close-up view of these huge sea mammals in the cavernous enclaves of their natural habitat should not be missed—despite an odor not unlike sweat-soaked sneakers.

If you can’t observe the animals to your satisfaction in the cave, go 0.25 miles north of the concession entrance to the “rockwork” turnout, where the herd sometimes populate the rocky ledges several hundred feet below. It’s also a good place to snap a shot of the picturesque Heceta Head Lighthouse across the cove to the north from the turnout.