The Westeinderplassen is a complex of interconnected lakes located primarily within the municipality of Aalsmeer in North Holland, Netherlands. With a total surface area of approximately 10 square kilometres (2,500 acres), it is the largest freshwater body in the Randstad region. The lakes sit at coordinates 52°15′N 4°44′E, and the surrounding lakefront communities include Aalsmeer, Kudelstaart, Burgerveen, Leimuiden, and Rijsenhout.

The northern portion of the lake system is particularly notable for its hundreds of small islands, making it geographically complex and interesting to navigate by paddle. Most of these islands are privately owned and accessible only by water. Four public recreational islands are available to visitors: Starteiland, De Heerlijkheid, the akkers of Ravenstein (near Kleine Brug), and Kleine Poelakker. Constructed beaches are present at some recreational areas. The northwestern section connects directly to the Ringvaart, a canal that carries significant commercial shipping traffic — paddlers venturing into that area should be aware of vessel traffic.

The recreational season runs from April through October, with the busiest activity concentrated during the warmer months. Swimming water quality around the recreational islands has been noted as good. The lake supports a variety of fish species including northern pike, common carp, grass carp, and European perch.

The lake system is heavily used for recreational boating and sailing during the season, which means paddlers can expect considerable motorized and sail traffic, particularly on sunny days. The islands and their varied character — some maintained as natural reserves, others used for agriculture — provide visual interest along any paddling route. Boat rental operations based in Aalsmeer offer sloops and guided cruises on the water, indicating well-developed waterside infrastructure in the area. The northwestern connection to the Ringvaart also means the lake links into a broader network of Dutch waterways, offering potential for extended touring beyond the lake itself.