On its southern side, Kealakekua Bay is rocky and exposed to regular northwest swells, so swimming and snorkeling conditions are poor. That said, Manini Beach makes a scenic, shady picnic spot. If you do want to take a dip, despite the scattered, sharp coral and ʻaʻa (rough, jagged lava) along the shoreline, the best ocean access is to your right upon arriving at the beach.
From Napoʻopoʻo Rd, turn left onto Puʻuhonua Rd, then right onto Manini Rd. There's limited roadside parking.