海をバックに記念写真撮ろうよ。

English Translation

Let’s get a picture of us with the sea in the background.

This is a good free translation. You can insert particle を between 写真 and 撮る. Dropping を makes the tone more casual.

記念写真 is a common phrase, meaning “a photo that will remind us of our visit to this place”. So, 記念写真 is usually taken as a group photo.