Two quite different businesses are sold as "Galápagos". One is the liveaboard cruise — four to fifteen nights on a small ship, the only way to reach the outer islands, and priced accordingly. The other is land-based: a room in Puerto Ayora and day boats out to whatever is within range, which costs a fraction as much and misses Fernandina and Genovesa entirely.
Diving is a third thing again, and the dive centres below are dive operations first. Every vessel that works the islands is licensed by the national park, and the operators here all say which of theirs is which.