The Potholes of Askola

A rocky slope in Askola named Kirnukallio features a set of cylindrical glacial potholes, called ”hiidenkirnuja” in Finnish. Twenty in all, they were ground into the bedrock face after the last ice age. This is the most extensive geological find of its kind in Finland to date. The area is always open and there is a small entrance fee.
The largest of the Askola potholes, named ”Jättiläisen kuhnepytty” (The Giant’s Tub) has a diameter of 4,2 m and is no less than 10,3 m deep.
The pothole array is located in the municipality of Askola, in the region of East Uusimaa, and is clearly marked by signposts along the Askola–Pukkila road (# 1635) .

On foot or by waterway

Access to Kirnukallio is by a footpath through the woods, starting out from the rest stop/parking lot on the Askola-Pukkila main road. The walk from here is about 500 m. There is also scenic path, about 300 m long and marked with red ribbons that skirts the crest of Kirnukallio and leads up to the entrance portal of the pothole area. The actual site is reached by a set of stairs with iron railings. The potholes in the rocky slope have their own nameplates and informative placards.

1. Riisipata 2. Professori Okko 3. Professori Asai 4. Mylly 5. Kattila 6. Kuppi 7. Jättiläisen kuhnepytty 8. Nojatuoli 9. Menninkäisen pesä 10. Vuorenhaltia 11. Vakka 12. Jäävaurio 13. Tonttu 14. Päärynä 15. Tulipunakukka 16. Kukkaro 17. Kohiseva 18. Koskenlaskija 19. Luiskahdus 20. Hiisi

Useful info

The pothole area is always open to visitors; however, there is no special wintertime maintenance.

An entrance fee is payable on location: either 2 € for adults and 1 € for children, or 4 € for families, or 10 € for school classes (Mobile Pay 35380). This fee is collected to support the continuing upkeep and maintenance of the area by local volunteers.
The terrain in the area consists of natural forest paths and rocks. Regrettably, prams and pushchairs are impracticable here. The pothole site itself is on a steep, rocky incline, and a set of safe stairs has been constructed to facilitate viewing. Disclaimer: visitors enter the area at their own risk. 

The pothole area is a suitable choice for outings such as picnics. Note, however, that there is no provision for open fires - in fact, fire making is strictly prohibited. Please show your consideration for the environment while visiting.

The Askola Society and the Askola local museum

he Askola Society (Askola-Seura ry) is responsible for the upkeep of the pothole area. The Society is an organisation active in regional and cultural affairs, and also maintains the Askola local museum.

The museum is located in Askola parish village at the address Nalkkilantie 4 (about 8 km from the pothole area), and is open to the public in the summer season only. Hours are from 11 a.m. to 2 p.m. every Sunday, June through August (closed over Midsummer).


The potholes were discovered one day in the summer of 1950, as Soini Järvelä of Askola and his son Jaakko were climbing up the steep Kirnukallio slope. Soini Järvelä happened to grab hold of a spruce sapling and pulled it out by the roots. This revealed a smooth cavity in the rock beneath, which turned out to be a pothole.

Many years later, in 1964, Jaakko Järvelä guided two interested visitors around the Kirnukallio site. They were the brothers Yrjö A. Jäntti and Lauri Jäntti, both captains of the publishing trade. Following this visit, the latter decided to make company funds available in order to finance the operation of excavating the holes.

The largest boulders had to be hoisted up with blocks and tackles. Many locals eagerly volunteered for the heavy restoration work, which was completed in the spring of 1965. An official inauguration ceremony was then held on Kirnukallio, whereby the giant cauldrons of Askola became a national attraction.

Pothole formation

According to the theory most accepted today, the potholes were formed at the end of the last ice age, more than 10 000 years ago, either in the ablation zone of the melting ice cap or in glacial crevasses into which meltwater flowed. This resulted in so-called moulins, shafts where detritus, rubble and boulders were swept along by the streaming water in a downward swirling motion. As they whirled round they ground a cavity into the rock, slowly expanding it with the passing of time. The process could take many hundreds of years.