Pitkäkoski is little more than a kilometre long, and it is the second longest rapids in the VantaaRiver. Common haze, beach groves and rugged spruce trees grow on both sides of the rapids. The riverbank on the Helsinki side, especially, is very steep in some areas, and parts of it collapse into the river occasionally due to erosion.
The nutrient-rich soil of the riverbank supports lush vegetation. The trees in the grove have grown exceptionally tall and the largest spruces and silver birches, m…ore than 100 years old, are nearly 30 metres tall. The shrub layer is filled with fly honeysuckle, mountain currant, guelder-rose and common hazel. The dampest spots also have blackberry bushes. Beautiful early bloomers at Pitkäkoski include species such as buttercups, chickweeds, windflowers and riverside marsh-marigolds.
The diverse bird species of Pitkäkoski comprise, among other species, the spotted nutcracker, common sandpiper, greenish warbler, hawfinch, common chiffchaff, and wood warbler. Every year, white-throated dippers migrate to the area from the north to spend the winter along running water. When the water surface is low, it is possible to spot thick shelled river mussels, a common species in the Vantaa River, at the bottom of the river. The thick shelled river mussel is an endangered species strictly protected by the European Union. Occasionally, you can also see otters chasing fish in the river.