I want to go to Nanjing Underwater World. I live in Yangzhou.

You are advised to take high-speed train from Yangzhou to NJ Railway Station first.
The train schedules are from 06:46 to 22:35. The duration is around an hour. The ticket fare of second class seat is CNY37.5 and first class seat is CNY58. After arriving, you can take metro line 1 to Xinjiekou Station and line 2 to Xiamafang Station, Exit 2. Then transfer to tourist bus line 2 to the destination directly.