The Dana expeditions were four Danish research expeditions undertaken by the Dana I and Dana II. They were funded in part by the Carlsberg Foundation and led by Johannes Schmidt. The first three expeditions took place from 1920 to 1922 and the fourth and final was from 1928 to 1930. They centered around investigating the breeding of eels. The first two expeditions allowed Schmidt to prove his theory that European eels migrate to the Sargasso Sea to spawn. The final expedition traveled to the Indian Ocean and gathered numerous samples.