Transvulcania

Transvulcania is a long distance race, considered one of the hardest mountain-ultramarathons in the world and one of the most important in Spain. The total route has a length of 73.3 km with a cumulative elevation gain of 4,415 m and elevation loss of 4,110 m. The race has taken place on the island of La Palma since 2009, with the participation of many international runners.Over time, additional races have been added to the original Transvulcania utramarathon proper, currently:

Half-marathon, 24 km with a cumulative elevation gain of 2,201 m and elevation loss of 669 m

Source: Wikipedia