YOU SAID:

I was going to fall down a very high mountain that was beside the ocean of another country that wasn't mine

INTO JAPANESE

私のものではない別の国の海の横にある非常に高い山に落ちるつもりだった

BACK INTO ENGLISH

I was going to fall on a very high mountain next to the sea in another country not mine

INTO JAPANESE

私は私の国ではなく、別の国の海の横にある非常に高い山に落ちるつもりだった

BACK INTO ENGLISH

I was going to fall into a very high mountain next to the sea in another country, not my country

INTO JAPANESE

私は自分の国ではなく、別の国の海の横にある非常に高い山に落ちるつもりでした

BACK INTO ENGLISH

I was going to fall on a very high mountain next to the sea of another country, not my own country

INTO JAPANESE

私は自分の国ではなく、他の国の海の横にある非常に高い山に落ちるつもりでした

BACK INTO ENGLISH

I was going to fall on a very high mountain next to the sea in other countries, not my own

INTO JAPANESE

私は自分の国ではなく、他の国の海の横にある非常に高い山に落ちるつもりでした

BACK INTO ENGLISH

I was going to fall on a very high mountain next to the sea in other countries, not my own