Hotel Zone WiFi decent but Riviera Maya cenotes and Mayan sites have spotty coverage.

Telcel SIM cards at CUN airport: 300 pesos for 7 days unlimited. Excellent coverage to Tulum, Cobá, even Valladolid. Buy at official Telcel counter only - avoid resellers.

Pocket WiFi rental: 200 pesos/day but dies in Yucatán heat. Skip it.

US carriers: Verizon Mexico Pass works well. AT&T decent. T-Mobile includes Mexico but throttles after 5GB.

Download offline maps before leaving Hotel Zone. Zero cell towers between Cancún and Ek Balam ruins.