YOU SAID:
I went to see the sea, but never saw a seal.
INTO JAPANESE
私は海を見に行ったが、アザラシを見たことがなかった。
BACK INTO ENGLISH
I went to see the sea, but I had never seen a seal.
INTO JAPANESE
私は海を見に行ったが、アザラシを見たことがなかった。
BACK INTO ENGLISH
I went to see the sea, but I had never seen a seal.
That didn't even make that much sense in English.