Vistula River is something exceptional and you shouldn`t skip this part of the city before you leave. While the left side offers a few kilometer promanade, the right side is not regulated and remains wild. Warsaw is the only European capital with a wild river bank. It`s a nature reserve with several natural sand beaches. In 2016 The Guardian placed the Vistula’s beaches in Warsaw among the ten best urban beaches in the world.
Everyone will tell you that Poniatówka Beach is the best. I definitely would. It`s the biggest from all the beaches and it`s located just two-three tram stops from the city center. Although I usully go there by bike, and you can use Veturilo city bikes that stations spread across the city. There is one also right on the beach, so just park it here.
The beach is located near the Poniatowski Bridge and the National Stadium. It offers free beach chairs that you can take from a small kiosk. You don`t need any ID, but you should return them before 7:00 pm.
There is a very modern playground, kayak rental and water tram stop taking people to the other side of the river every 15-20 minutes. MOSiR bar and restaurant offers a great outdoor space. From my personal experience I can tell you they serve decent burgers and delicious sweet potato fries. However their menu offers more than that.
There is a ten kilometer path meandering between trees along the river. It`s one of my favourite bike lanes in Warsaw. You can check it out on your way to the beach if you decide to take a bike. Ride from the city center down Tamka Street, then cross the Świętokrzyski Bridge. Turning right from the bridge you will see a road leading under it (look for a climbing wall). Under the bridge you will see the path, just turn left and go South. After few minutes you will get to Poniatówka. If you like walking you can choose the same way to get there.
Please remember that swimming in the river is not allowed cause it`s not regulated and has a strong current.