I organised a first year, start of year field trip for 120-200 new undergraduates in the UK (various destinations).
Since we would not know the students well, and importantly they would not know US or their peers well so may not feel comfortable disclosing concerns, detailed planning and information sharing was crucial. This began by having students complete personal details forms which were screened by staff (necessary – one said they had no dietary restrictions, but on the medical details section said they were deathly allergic to peanuts!), and individual meetings could then be had with students who might need adjustments. We also liaised early on with the accommodation providers over e.g. dietary issues, needs for different types of rooms etc. (some students need an individual room, ground floor, etc.).
A very detailed booklet about the trip was prepared for both staff and students, covering the accommodation as well as all the activities planned, with information about the locations of toilets and shops, distances, and information about issues like a stepped path and a view point with a steep drop – we also had photographs of these available. The staff handbook had extra information about points at which a support person would be able to pick up students if they needed a lift to the next stop rather than walking, or to leave the group for a while or return to the accommodation, the location of places to sit along the route etc. Students were divided into small groups of 7-8 and these were joined in clusters of 21-24, and each cluster had allocated staff members who had been briefed about any issues in their cluster. These booklets were shared at least a week before the trip, and both allowed students to familiarise themselves with the environment and gave written information about the purpose of each stop, the kinds of notes or field sketches we would expect, what topics would be discussed etc. which they carried in the field so could check as needed to refresh memory, ensure they'd understood etc.
Getting approval for higher than normal staff numbers was a challenge but proved vital – over the course of several years, staff had to be pulled from the main trip to look after an actively suicidal student, a diabetic student who misjudged their intakes, a student who fell out of a bunk bed and broke a wrist, a bad reaction to an insect bite, several migraines and anxiety attacks where students just needed a bit of time out, and a lot of lifts for students with varied mobility concerns. Having plenty of staff was vital for staff well-being (including myself – I have Generalised Anxiety Disorder), and overall the trips were very popular with students and clearly helped their bonding as a cohort.