Hello Shamus!

This is Loryanna with Viator. Just responding to your inquiry!

We do use secured servers for our reservations, so your purchase will be safe no matter if you make it by phone or through our booking website. I hope this information helps!

I've pre-booked Viator excursions for trips I've made to Spain and Mexico. Very cost effective, and the trips were OK, guides were decent, though they tend to operate their coaches at full capacity. I did once have some minor problems contacting them in resort - make very sure you have a phone number before you go - AND make sure you know how to dial it on your UK mobile phone. (Sometimes it's not how you expect)