Opened in 2004 as part of an art project to enliven the city’s riverbanks, the Arena Berlin is a former bus depot turned music hall and entertainment complex that now hosts events as diverse as roller derby and rap concerts. One of its biggest draws is the Badeschiff, a heated swimming pool built out of an old barge that floats in the Spree River. A dock connects the pool of clear blue water to a beach area, providing plenty of space for visitors to relax, soak in the rays, or even play some beach volleyball. After sunset, the space transforms into a beach club with DJs and colorful drinks to add to the atmosphere. Wind up the evening with a moonlight dip, the lit-up city across the water providing an unforgettable backdrop.