There are three swimming places around the city: the Tbilisi Sea, Turtle lake and Lisi lake.
Tbilisi sea is not actually a sea, but a fresh water reservoir; one of the drinking water sources for Tbilisians. The reason why it’s nicknamed “sea” is unclear. Probably, because it’s deep and big. The lake has a length of 8.75 km and a width of 2.85 km. Maximum depth is 45 m and an average depth is 26.6 m. The water is a bit cool during hot summers and provides a natural getaway during the scorching hot summers. The construction of the park and a recreational zones are currently in process. Meanwhile, visitors can enjoy a few cafes around the reservoir. Also, they can rent a sun tent, water scooter or boat. Also, just across the road there is the Chronicle of Georgia. It is a 16 pillar monument, which depicts scenes from history of Georgia, as well as the life of Christ.
Lisi Lake is small and cozy. It’s shallow and the water heats up rather quickly. There are a few fishing spots and a nice paved trail around it (3 kilometres). There are cafes, Dunking Donuts, a small park, children playgrounds and bike rental available. You can get to Lisi lake by minibus (marshrutka), taxi or a car.
The third one is Turtle lake or Kus Tba in Georgian. It got its name from turtles, who live abundantly around there. It is located high on Mtatsminda mountain, so it is cooler than rest of the city. There is an amazing trail around it. There are cafes, bars and restaurants. Also, a paddle boat is available for rent. Nearby, there is an Open Air Museum of Ethnography, where visitor walk around traditional Georgian houses. You can get there by taxi or a car.
Mtkvari river (Kura river) is not sutable for swimming or fishing, though, some locals still fishing on the banks of the river.