We are arriving from Buenos Aires to Montevideo by ferry/hydrofoil for a 3 night stay before returning to Buenos Aires the same way. I have read that Uruguay requires to see a valid Yellow Fever Vaccination Certificate or Exemption Certificate from travellers entering from certain countries. 1) Is Argentina one of those countries? 2) When is this documentation requested for water entries? 3) Do they accept the Exemption Certificate? 4) Is this worth asking the nearest Uruguayan embassy about, or is it more variable locally?