. "*Cargo Space: 1 \n*Can explore rival territory w/o triggering war"@en . "3"^^ . . "Frigate"@en . "Caravel (Civ4)"@en . "60"^^ . "3"^^ . . "Caravel"@en . "Cost N/A Upgrades to Frigateor Submarine N/A Required technologies N/A Required resources N/A Other attributes N/A The Caravel is replaced by the following unique units: \n* Carrack (Portugal) The following units can be upgraded to Caravels: \n* Trieme"@en . "Cost N/A Upgrades to Frigateor Submarine N/A Required technologies N/A Required resources N/A Other attributes N/A The Caravel is replaced by the following unique units: \n* Carrack (Portugal) The following units can be upgraded to Caravels: \n* Trieme"@en . "Submarine"@en . "Naval Unit"@en .