Tunnels a shore dive? SeaSport and Fathom Five both run their boats to that site from Koloa area Harbor. Its is a few hundred yards. It could be done from shore, but with 3' to 4' rollers, I would not try it. Not to mention warm water to spray in your wetsuit and a quick run back to the docks to use the bathroom is mighty convenient.
The Koloa landing is a shore dive, and an excellent one if I might say. Many endemic species and shallow enough to get well over 60 minutes per tank.
I like all the outfits I dove with, but I can say that when something wasn't right, Fathom Five worked their tails off to make things better and did a great job. But I had a chance to meet most of the folks at most of the dive shops and they are all professional and skilled. There is a lot of competition on the island, they all do well. My favorite was Fathom Five because of the personal service.