While other careers on this page typically have a conventional route, an expedition/volunteering coordinator doesn't necessarily. Most recommend that you get an undergraduate degree in anything from Business Studies to Social Sciences, but a degree isn't necessarily the most important part of this role and isn't always needed. What is needed is experience: volunteer and take part in expeditions as much as you are able to deepen your understanding as to what is needed to organise such events. Some universities and colleges even run courses on Volunteer Management. Although a UK resource, this website is good for more info.