Hi Clive! There is a mixture of road and paths. There are cycle paths until the first ferry between Pargas and Nagu. From there onwards it is roads. If you let the ferry traffic pass you can cycle in peace until the next ferry. There are options for quieter roads in the route descriptions. The elevation curve under the map shows the road surface. Cyclists can take the ferry Hakenpää-Teersalo on stage 6 to avoid the busier roads. As you approach Naantali there are cycle paths again. Using this,the busiest sections are between the Iniö ferry and Taivasalo on stage 6 10km and the route through Nagu island on the main road, by using the quieter roads this will also be ca 10km although the main road has better asfalt.