Condado Lagoon (Laguna de Condado) is a small lagoon in between Condado and Old San Juan.  It is wonderful because it has no waves.  There are some rocks on the right side that keep the large waves out.  On the left side is a bridge (Puente Dos Hermanos) that connects Condado to Old San Juan.  Condado Plaza Hotel and Casino is infront of it, on that same corner. Condado Lagoon is a walking distance from the local hotels around the area, about a 7 -10 minute walk from La Concha Resort.  Good place for kids to swim.  There is a small park at the entrance.   You definitely need water shoes because of the rocks and shells on the bottom.