English Translation
Dangers give relish to an adventure.
Unnatural translation for two reasons.
First, particle が is unnatural. 冒険が should be replaced with 冒険は.
Second, 危険がある itself is a natural phrase but it’s not a good collocation with おもしろい (or 面白い).
My alternative translation is:
危険こそが冒険の醍醐味だ。（きけんこそがぼうけんのだいごみだ）
醍醐味 means “real joy”. You can find many example sentences with 醍醐味 here on 英辞郎.