* The GUAP [Guadalupe Underwater Archeological Preserve] is the most popular dive site in the DR, it's ~25 feet and absolutely beautiful. Sits right along a long reef that's full of fish, lobster, the occasional octopus, and has a great, diverse range of corals (D. cylindrus is my favorite there) Adjacent to Viva Dominicus Beach and Viva Dominicus Palace in Bayahibe
*Another great dive is the Caballo Blanco, 18th century wreck but also has 16th century Spanish anchor and artifacts. Dive is deeper, around 45 feet, but very nice and also gorgeous reef
*Captain Kidd's ship is off of Catalina island, in 6-8 feet of water. Site itself isn't great, but the history is really cool. Terrific wall dive right next to the wreck as well, easy and beautiful 100 ft dive
* Dive shop we used was Scuba Fun in Bayahibe, really stellar team. Organized and friendly, they do certifications as well as charters.
* Hotel we stayed in is Be Live Collection Canoa in La Romana outside of Punta Cana. Nice resort, lots of couples and families, but somewhat isolated. Beach is lovely, and it's right next to a nature preserve
* Viva Wyndham Dominica Beach was the resort we were supposed to be at. Younger crowed, lots of partying, also gorgeous beach. Guadalupe underwater archaeological preserve is directly off the Viva beach
Overall, the DR has good reefs and dive sites, but diving on historic shipwreck sites is what makes it so special. If you're looking for a non-ocean day, check out the Taino sites (either the cave tours or the flooded caverns at La Aleta.