INS Chapal is a warship which has been converted into a museum and now open for visitors. You are shown a short film about the life on the voyage and you get to explore the entire width of the ship to get a glimpse of the voyager’s life. Alongside is the Karwar Aquarium which houses a wide variety of fish. I initially thought it would be nothing great but the sheer variety surprised me. Both these are just on the Tagore Beach, so you could couple a visit to these places along with the beach.
This is the ancient water town called 'Wu Zhen'. Do note this place is not in Hang Zhou city but it is about a 1.5 hour taxi ride away from the city. I wouldn't highly recommend you to visit this place if you are running a tight schedule in Hang Zhou as you are required to spend about 3 hours in total travelling to and fro from this water town. But if you have extra time on hand, it won't hurt to visit this place because it definitely has its "traditional feel" to it.