Halmsjön, Natural lake in Uppland region, Sweden.

Halmsjön is a lake in Sigtuna Municipality, Stockholm County, about 40 km north of Stockholm. It lies 30 m above sea level, covers 0.23 km² and measures roughly 0.7 km from north to south and east to west. Its shores are wooded, with a hill rising to 62 m about 1.6 km away.

Halmsjön is a small lake of about 0.23 square kilometres in Sigtuna Municipality, Stockholm County, roughly 40 km north of Stockholm. It lies about 30 metres above sea level, with a wooded hill rising to 62 metres within 1.6 km of its shore. The surrounding land is forested, and the lake measures about 0.7 km across in both directions.

Halmsjön is a small lake of about 0.23 square kilometres in Sigtuna Municipality, roughly 40 km north of Stockholm. Its surface lies 30 metres above sea level, and the surrounding woodland is dominated by coniferous forest. The lake is one of three Swedish waters named Halmsjön, the others lying in Vårgårda and Kramfors municipalities.

The lake has multiple access points around its perimeter where visitors can approach the water and enjoy the surroundings. The best time to visit is during warmer months when conditions are most comfortable for walking and fishing.

Halmsjön is the lake in Sigtuna Municipality, Stockholm County, about 40 km north of Stockholm, not the identically named lakes in Västergötland and Ångermanland. It lies 30 m above sea level, covers 0.23 km² and measures roughly 0.7 km across; the nearest hill rises to 62 m about 1.6 km away.