The Coral Dreams Dive Shop on Contadora offers diving and snorkeling tours, and rents tanks and gear to PADI-certified divers. They can also teach beginners how to scuba dive.
Guillermo can arrange to have the dive boat come pick you up at the dock here on Saboga, or at the beach in front of the Paula Nani Beach restaurant.
His website and contact information is at https://coral-dreams.com/
They also do whale-watching tours between July and September. Highly recommended!