Not sure what is the "3rd finger" either. Is it Kulahua Point? (Just beyond that point, on the dry shelf, are several large boulders known as "Pele's followers".) I've been around the point to Pupukea Beach but never ventured more than about 50m from shore. All the way to Pupukea Beach, there's only a fairly shallow shelf. There may be more tubes and caverns in the deeper water beyond. I don't know.
The only big cavern that immediately comes to mind, and everybody knows about, is the one just before Kulalua Pt. Using GoogleEarth, the coordinates of the cavern are approx. lat. 21.654363, lon. -158.063473. Back in the day, the cavern was choked lousy with lobsters; spiny, slipper, Hawaiian Reef. Harlequin shrimps, too. The deep recesses in the cavern roof might still have a few that haven't been blasted by exhaust bubbles. (Other large tubes are at: 21.652781/-158.062910, 21.652446/-158.062954, 21.652135/-158.062434)
Current toward Waimea Bay can be a problem outside the lee of Kulahua Pt. One plan is to start the dive at Pupukea Beach. Drive (or walk if you're sturdy enough or don't want to risk your car locks being punched) past Shark's Cove, take any left onto Ke Iki Road, backtrack toward the Cove, and there's a public right-of-way leading to the corner of Pupukea Beach and the limestone shelf. Start there and drift back toward the Cove. Figuring out where to break the turn into the Cove can be a problem; popping up for look will help. That's one reason why I never got too far offshore; I'd keep oriented by contouring along the shelf.