You can enter Päijänne national park by kayak from several places but the most popular place for take-off is from Padasjoki village from the western side of the park or from Pulkkilanharju from the south-east direction. In either case it is better to check wind forecast because there are huge open lake to cross and weather can turn from the sunniest day to the very windy and murky in no time.
Kayaking in Päijänne national park can be exciting, lake Päijänne is the second largest lake in Finland. The national park itself consists of several islands of which Kelvenne is the biggest with fine sandy beaches. Good site for overall information of Päijänne national park is nationalparks.fi.
My trip started from Padasjoki harbor though I learned later that there is a better place for start a kilometre north of the harbor near Mainiemi.
Best places for more quiet camping/stops are those harbors which can be reached only by kayaks, canoes or smaller boats. Those sites are:
1. Isohieta beach on Kelvenne island (long beach, enough room even in “tourist” season, best choice)
2. Nimetön on Kelvenne island (a bit dark shore, check the western side)
3. Lietsaari (sandy beaches on both side, not for camping unfortunately)
Check also Hinttolanhiekka on the eastern side of Kelvenne island, sandy beach and quiet popular. There are a lot campfire sites and harbours but camping is allowed only in a few places.
You can easily find place place for your tent on Isohieta beach on Kelvenne island and enjoy your day either hiking the 8 km trail from one end to another of Kelvenne island or swim or snorkel in the shallow waters by the beach. When camping make sure to protect your food properly because there is a at least a small population of nosy badgers on the island and they will check your supplies in the night.
Because Päijänne national park can be reached quite easily from Padasjoki, it is suitable for weekend trips though there are a lot of places for longer exploration. There can be a lot of boats around in July which is the busiest season, but on other times there is peace and space.