Arnold, CA…Big Trees Fitness Evening Swim Series Continues With a Saturday Night Dance Party. We’re opening the dance floor to a live dj at the Big Trees Fitness Center Saturdays through the Summer Pool Season from 7:00 to 10:00 PM. The pool is open until dusk, and we’re serving great food and drink from our new menu. Come join us for a good time and an evening swim at the Big Trees Fitness Center! Big Trees Fitness Center 2116 Hwy 4 Arnold , CA (209) 795-9965