Concept Faculty for 2026
Mark Frederikse
Mark is a military and emergency physician. He has worked in the UK, Australia, and the Netherlands. In 2012, he became a certified PADI dive instructor. In addition to teaching various courses (AWLS, DMLS, AMLS, TECC), he works as a hyperbaric physician, conducts medical repatriations, and served as a ship’s doctor on large American cruise ships prior to the pandemic.
Jacco Veldhuyzen
Jacco works as an emergency physician in the region between the Gouw and Zaan waterways in the Netherlands. He is a certified diving medical officer and has served as a ship’s doctor in both the Arctic and Antarctic. During his training, he worked and travelled extensively around the world, including placements in Suriname, Sint Maarten, and the UK. He has been an instructor with Outdoor Medicine since 2016. In his free time, he enjoys diving, mountain biking, canoeing, and hiking.
Leonieke Vlaanderen
Leonieke trained as an emergency physician in both the Netherlands and the UK. She currently works as a consultant in emergency medicine and with the air ambulance in England. In the Netherlands, she served with the Royal Navy as a Search & Rescue physician. She is also a medical advisor for the Brighton Lifeboat, having previously been part of the crew herself. Her other passions include cycling, running, and reading.
Annemarie Wuister
Annemarie works as a general practitioner in Rotterdam and The Hague. During her medical training, she worked in India and Peru and has a strong love for travel and adventure. She has worked as a physician in several refugee camps and currently serves as a ship’s doctor in both the Arctic and Antarctic. She lives in The Hague, where she is an avid kitesurfer. Annemarie is also a certified offshore catamaran instructor and responsible for CPR and first aid training. Her holidays often involve multi-day hut-to-hut treks in the mountains.
Titus Schönberger
Titus has been an emergency physician since 2010 and is a passionate instructor in various fields of acute care, including emergency interventions, point-of-care ultrasound, ambulance medicine, and courses provided through Outdoor Medicine. He has experience as a ship’s doctor in Antarctica and loves exploring the wild and open world—both on land and at sea—challenging the elements through sport and adventure. He has now set foot on every continent with his size 45 boots.
Loes de Vaan
Loes is an emergency physician with a special interest in planetary health. She regularly collaborates with Greenpeace. For example, she was part of a marine biology expedition to the Galápagos Islands, where she assisted in research on sharks and their migration routes. She also served as the ship’s doctor on the Rainbow Warrior during a mission to stop deep-sea mining in the Pacific Ocean.
Loes is always looking for new challenges. In the past, she set up a tropical medicine project at the University of Khartoum in Sudan, was part of a medical mission by hovercraft in southern Madagascar, and was involved as an expedition doctor in a survival program led by former commandos in the Norwegian fjords. She has been working with Outdoor Medicine since 2019.
Wouter Jetten
Wouter is an emergency physician who has worked abroad on a project basis as a lecturer and expedition doctor. He is one of the founders of Outdoor Medicine. In the Netherlands, he lived for many years on a sailing Groninger tjalk (a traditional Dutch barge), which he often took out on the water. Wouter also worked as a ship’s doctor for Greenpeace in the Arctic and Caribbean, in a rural hospital in northern Cameroon, and as an expedition doctor on Kilimanjaro. He also has extensive experience as an instructor of the international STCW/IMO course “Medical Care on Board” for nautical officers. Wouter currently works as a military emergency physician with the Royal Netherlands Navy, where he spent four months in the Middle East aboard a floating hospital.
