you are likely to find Cave in/at/on Desert. Desert is the opposite of Sea. 
Bat is a type of Animal. Mate is a type of Animal. Mate is related to Tea. Tea is related to Boil. 
Cave --AtLocation--> Desert <--Antonym--> Sea 
Bat --IsA--> Animal <--IsA-- Mate <--RelatedTo--> Tea <--RelatedTo--> Boil 