Bathe in the womb-like waters of Agua Caliente Regional Park, and try a moonlight trek on the Moonlight Trail.

Summer's hellishly hot siege of the Anza-Borrego Desert is nearly over, and Agua Caliente Regional Park (adjoining Anza-Borrego) is back open for business. For the next couple of weeks the demand for Agua Caliente's campsites won't be intense -- but sooner or later, you'll have to reserve a spot if you intend to stay overnight (858-565-3600 is the county parks department reservation line).

There are two ways to get to Agua Caliente, both about equidistant from central San Diego. Option one: East on Interstate 8 to Ocotillo, then northwest on County Highway S-2 for about 27 miles. Option two: Eastward through Julian, down State Highway 78 to Scissors Crossing, then southeast for 22 miles along Highway S-2. It's best to make the journey a loop trip, so you can maximize the scenic variety.

Agua Caliente is San Diego County's best-known, open-to-the-public geothermal area. An offshoot of the Elsinore Fault is responsible for the upwelling of warm to hot water here. The Elsinore Fault itself passes through the Lake Elsinore area and Warner Springs, where hot springs are also found. Agua Caliente's outdoor bathing pool is kept at a natural 96 degrees, while the indoor "therapeutic" pool is heated to over 100 degrees.

A small network of trails radiates outward from the bathing pool and campground area. Moonlight Trail is a great one to start with, particularly (this time of year) during late afternoon, when evening shadows arrive early due to the sharply rising mountains to the west. The well-marked, 1.5-mile trail starts from the south end of the campground, and climbs abruptly to a rock-strewn saddle. It then drops into a small dry wash named Moonlight Canyon, descends past some seeps and a little oasis of willows, and finally circles back to campground.

Moonlight treks on the Moonlight Trail are not only possible; they're simply magical this time of year, when the nighttime air is pleasantly warm (85 degrees or so) and, more importantly, dry. The weekend of October 6-8 coincides the full moon, which should rise after twilight and work its way upward to illuminate most of the trail by around 9 p.m.

This article contains information about a publicly owned recreation or wilderness area. Trails and pathways are not necessarily marked. Conditions can change rapidly. Hikers should be properly equipped and have safety and navigational skills.