Free: All time (July & August) Paris Beaches

Escape the heat and humidity in Paris during summer and head to Paris-Plages. For a month, the city sets up temporary artificial beaches running along the river Seine in the center of Paris and along the Bassin de la Villette in the northeast. All sort of activities can be found there besides the beach itself: tai-chi lessons, ballroom dancing, nautical fun and a library. Yes, a library. 

Address: Voie Georges Pompidou (center of Paris) and Bassin de la Villette (northeast of Paris)
Opening Hours: Daily 9am-12am
Direction: For Voie Georges Pompidou: Metro Line 1 to Louvre-Rivoli Station; Line 7 to Pont-Neuf Station; Line 1/4/7/11/14 to Châtelet Station; Line 1/11 to Hôtel de Ville; RER A/B/D to Châtelet-Les Halles; Bus 21/24/27/38/47/58/67/70/72/74/75/76/81/85. For Bassin de la Villette: Metro Line 2/5/7 to Jaurès, Line 7 to Crimée, Line 5 to Laumière, Bus 48/54