Big enough for anything you could bring
I purchased this bag for an upcoming beach trip and it was perfect. I ended up using it as my "personal item" on the plane because I wanted to be able to bring more stuff with me. It did fit under the seat (barely) but there was plenty of space for all my belongings and it worked well on the beach too. The fabric is more sturdy than cotton so it can withstand abrasive sand and seawater. It looks cute as well!