The couple undertook an expedition to the Caucasus in 1914 to return to Russia after the outbreak of the First World War. Back in the Netherlands, Visser gave lectures on his journey. In 1916 a second trip to Russia followed. After the war, Visser worked as an attaché in the Dutch parish in Stockholm in 1919. He was able to explore Finland in the following years, to make another trip to Switzerland and to visit the Arabian peninsula. In Stockholm, he met the well-known Swedish explorer Sven Hedin and discovered the idea of exploring the Karakoram. This mountain in the middle of Asia was still largely empty on maps. This fantasized Visser.