Three years of visiting Tulum and I never leave without....
Bug spray (a must if going anywhere around vegetation)
Benadryl, some of the no-see-ums and sand fleas are vicious
A flashlight w/red light (especially when walking on the beach and beach road at night) and RED for spotting turtles on the beach
Lots of 10-20 peso coins for tipping (for some reason it's harder to get change in Tulum, most restaurants will try and round up to avoid giving you small change)
Print-outs of all my confirmations for hotel, car rental, tours
Portable bio-friendly travel detergent, this way I can wash my clothes in a sink and hang them to dry. No more having to pack so many clothes!
Quart and gallon size ziplock bags for toting home dirty clothes, and anything collected on the beach
Hand sanitizer, sometimes there aren't any facilities if going "off the beaten path"
SPF 45 chapstick, nothing worse then burnt lips
Book light, most cabanas have little to no lighting at night
Spray-in hair detangler, for ladies with long hair like me the salt water can wreak havoc on your hair
What NOT to bring to Tulum....
Perfume, the bugs will eat you alive
Makeup, come on, a little vitamin D makes anyone look good