You can dive even if you can't swim. Discover Scuba Diving (DSD) limits depth to 12 meters with one-on-one instructor supervision. Before descending, you'll do a 15-minute session on mask clearing, regulator breathing, and ear equalization. As long as you're comfortable in water and can breathe normally, you're good. That said, practicing mask-on mouth-breathing in a pool or shallow sea beforehand dramatically reduces anxiety on the day.
Three main sites compared: Wuzhizhou Island (best visibility 8-15m, rich coral and fish, but priciest at 580-880 RMB/dive); West Island (visibility 5-10m, great value at 380-580 RMB, ideal for first-timers); Yalong Bay Underwater World (visibility 3-8m, cheapest at 280-380 RMB, but underwater scenery is mediocre). Beginners should start at West Island, then upgrade to Wuzhizhou for the better reef on dive two.
Pitfall warnings: ① Refuse street hustlers offering "150 RMB dives" — they're either unlicensed or pile on fees once you're underwater; ② Only use PADI or SSI-certified shops and ask to see instructor credentials; ③ Confirm underwater photos/video are included — standalone fees run 80-150 RMB; ④ No flying, alcohol, or cold symptoms 24 hours before diving; ⑤ Menstruation, pregnancy, heart disease, asthma, and epilepsy are contraindications; ⑥ No high-altitude travel or flying within 12 hours after diving.