The second, Ri Ri, is by far the prettiest blue hole/crystal river out of all the Santo blue holes. It is another 45 minute paddle farther south of Matevulu Blue Hole. Paddling up the entrance lagoon and crystal river is nothing short of magical! You can also visit both these blue holes by car as well, and at Ri Ri Blue hole you can choose to have locals paddle you up via outrigger canoe (ask the locals near the bridge going over the Ri Ri river).
The locals have gone to a lot of effort to provide platforms, bathrooms and change areas to make this blue hole easily accessible. Cost is 500vt per person.