This island is very close to the city, you can go there by a paid motor boat and on working days it's a great chance that you will be the only one on the beach. There are many tourist camps on the island where you can stay on weekend.
There's a beautiful view of the city and Saratov bridge from the Green Island beach. You can lay on a warm sand and look on the city, or walk deep into the island and find a great place for fishing, and then cook the fish on the fire.
You may find some drown ship near the island