On Ultramars website it says a roundtrip ticket from Puerto Juarez to Isla Mujeres is $300 USD. But a roundtrip ticket from any of the other 3 locations in Cancun is only $19 USD. Am I missing something here? Everything I have read online says to take a cab or private transfer from the airport the Puerto Juarez ferry location. Why is is so much more expensive from Puerto Juarez?