Despite of the typhoon, my friends were swimming in the sea.

英訳に間違いが有れば正してください。

台風にもかかわらず友達海で泳いでいた。
Despite of the typhoon, my friends were swimming in the sea.

答え ofが不要。

Despite the typhoon, my friends were swimming in the sea.

despite
…にもかかわらずという意味の前置詞