Rendezvous Beach is the most accessible swimming beach on the Utah side of Bear Lake. The south-shore water is shallow, the sand is broad enough for families to spread out, and the state park facilities make it easier than the wilder pullouts around the lake.
It is not a secret. On hot July weekends the beach fills with families, coolers, inflatable toys, and the full soundtrack of summer vacation. Come early if you want a good spot, or aim for a weekday when the lake feels much larger.