The only way to get to Isla del Sol is by boat via the Lake Titicaca. Several tour companies in Copacabana offer daily boat services to the island. The ferry is about 1h30 one-way and the ride costs 20 Bolivianos per person. There are no motor vehicles on Isla del Sol.
Uyuni Salt Flat
The easiest way to get there is by bus. Most major cities in Bolivia offer bus routes to Uyuni.