Starting from late January, Estonia opens its ice roads. Usually, it lasts till late March, when the Baltic Sea surface is sufficiently frozen. During that time you can visit even more places than in summer, as ice roads connect the mainland with the islands. Driving on these roads is regulated by special rules. You shouldn't drive too slow, the lag between cars can't be less than 2 min, seatbelts are forbidden, as you may need to leave the car very fast, and you can not drive after sunset. Of course, vehicles havier than 2.5 tonnes are not allowed on such roads. The longest ice road in Europe is 26 km long road connecting the Estonian mainland and second-largest island Hiiumaa. Estonia has 6 such roads, but they all depend on weather conditions. The ice surface should be thick and strong enough, at least 22 cm (8.7 in), to be officially opened.