YOU SAID:
swimming in the swimming pool went swimmingly today.
INTO JAPANESE
今日はプールで泳いで泳ぎに行きました。
BACK INTO ENGLISH
I went swimming in the pool today.
INTO JAPANESE
今日はプールに泳ぎに行きました。
BACK INTO ENGLISH
I went swimming in the pool today.
That didn't even make that much sense in English.