Trylen is a small lake 17 km (10 mi) south of central Stockholm, Sweden.

With its catchment area characterized by morass and pine covered rock faces, Trylen is a popular spot for walking and bathing.

[2] Nutrients only reaches the lake from the air, which makes water quality high.

[2] An inventory in 1998 documented common reed, water horsetail, Menyanthes, yellow water-lily, white water-lily, floating-leaf pondweed, and flatleaf bladderwort.

Toads were reported in the lake in 2004, as were dragonflies such as brown hawkers and brilliant emerald.