Rick Mariscal was thrilled when he found out that he was getting an extra day off from work to start a three-day weekend.

So the baseball coach from Richmond rounded up three of his players, jumped in the car and headed to Caswell State Park with a fleet of traditional black inner tubes in tow.

Not even the cold water took away from the fun of floating the Stanislaus River.

“There’s nothing better than taking some time to cruise down the river,” Mariscal said as he and his three players worked their way back up to their starting point. “It’s a chance to get out on the water and enjoy the sun.

“The river is flowing and it’s a little bit cold because of all of the snow and you don’t quite feel as much after a while. But it’s nice to be out there.”

Mariscal and his crew represented a large contingency of Bay Area visitors that are taking advantage of one of the true hidden jewels of the California State Park system. Tucked in along the Stanislaus River with old growth trees towering over campsites, the secluded spot at the end of Austin Road drew several San Jose families that make the trek every year.

Jazmine Linares spent most of Friday afternoon unpacking at her campsite after setting up her tent.

The drive from San Jose to Caswell was relatively smooth. With her boyfriend Luis by her side Linares was waiting for the rest of her family to arrive for a weekend of fun at a riverfront campsite.

“We like it here because it’s really shady and the water is right there. It’s so close to the campsite and that makes it really convenient to get in and out,” Linares said. “We’ve been here before for Fourth of July weekend, and we’ve been here for Memorial Day weekend as well.

“It’s a fun place to be and it’s great when your entire family can get together and enjoy something like this together.”

But as fellow San Jose and Caswell camper Daniel Robles knows, reservations for busy weekends like Fourth of July are needed in advance if you’re looking to capture a site.

All of the campsites are full for tonight and Sunday nights. Day use is still available.

But that doesn’t bother Robles, who will be spending the weekend with his wife Lucy and their three small daughters unwinding beneath the thick grove of oak trees.

He made his reservations four months ago.

“We’ve been coming out here for the last six years. Sometimes we come this weekend, and sometimes we come in September for Labor Day,” Robles said as he took a break from hammering in tent stakes. “It’s a good chance for the family to get away, and a great place to get some rest and relaxation.”

Day use at Caswell State Park will still be allowed throughout the weekend. The cost is $8 per vehicle. To get to Caswell Park, exit on Highway 99 at Austin Road and head south. The road will dead end at the park entrance.