The Pitkäkoski groves are situated slightly further from Haltiala in the northwestern section of Central Park (Keskuspuisto) on either side of the Vantaanjoki river. The area is owned by the cities of Helsinki and Vantaa: 4.74 hectares on the Helsinki side of the river and 12.8 hectares on the Vantaa side. The area was granted protection status in on 10 May 1984 to preserve the valuable groves and river nature. The protected area on the Vantaa side of the river was extended in 2007.
The Pitkäkoski rapids stretch for around one kilometre and are the longest natural rapids in the lower reaches of the river. Lush conifer groves grow along either side of the rapids. Among the conifers, which are over 100 years old, grow hazel bushes, fly honeysuckle, mezereon and colourful flowering plants such as touch-me-not balsams, spring peas and alternate-leaved golden saxifrage. Information boards and marked trails make it easy to explore the nature in the area. There are also viewing platforms on either side of the river.