Complex sentence: In the summer (Dec-Feb) a regular boat service takes passengers from Villa O'Higgins across the O'Higgins/San Martín Lake to Candelario Mansilla, from where it is possible to cross the border into Argentina via a footpath (no road).
Split into simpler sentences: In the summer (Dec-Feb) there are regular boats from Villa O'Higgins over the Lago O'Higgins lake to Candelario Mansilla. From Candelario Mansilla it is possible to cross the border into Argentina via a footpath (no road).