People: Kids Hold Hands
While it may be tempting to want finished looking backdrops for your portraits this picture shows that it isn't always necessary. In fact, the rough, unfinished look of the sand with strong, late afternoon shadows casts a different effect on the children holding hands.
Beach Effects
The sand and beach offer particular challenges, especially in urban areas where millions flock to them and leave behind trash. Portraits are more challenging to accomplish under these conditions because most people like context, but not dirt and trash.
Picture from the Pier
If you're going to do portraits of children and adults taken from different angles, you'll need some ground help when you are shooting from an above location such as a pier. Kids will quickly move onto the next adventure if someone doesn't work with them to keep them looking in a particular direction. This is evidenced in the portrait here with a little boy looking down. All you can see is his hat.