YOU SAID:
I swam under the sea, and into the sky
INTO JAPANESE
海の中や空に泳いだ
BACK INTO ENGLISH
I swam in the sea and the sky
INTO JAPANESE
海と空に泳いだ
BACK INTO ENGLISH
I swam into the sky and the sky
INTO JAPANESE
私は空と空に泳いだ
BACK INTO ENGLISH
I swam in the sky and the sky
INTO JAPANESE
私は空と空に泳ぎました
BACK INTO ENGLISH
I swam in the sky and the sky
That didn't even make that much sense in English.