There is a sidewalk between the ocean and the resort which runs down to Whalers Village and then a bit further. Black Rock is just a little walk (20-25 min) down from the resort past Whalers Village. You can also catch the little shuttle bus that stops right behind the Marriott down to Whalers Village if you want to shorten the hike.
The overall best snorkeling spot (In our opinion) is Honolua Bay. It’s about a 20 min drive up the coast from the Marriott. You can stick it in maps to get there. Signs are along the road. You need to get there early..like 8-8:30 am because parking is sparse but turtles abound…tons of different kinds of fish etc… You walk a tiny bit on a wide trail through the rainforest. ( it’s really pretty) The entry is a little tricky because the beach is mainly large smooth rock ( not sharp volcanic )…bring water shoes. Swim to the right out into the bay.
(Cool waterspout in that area too! )
Traci S.