In the centre is a 'smalschip' (a small Dutch sprit-rigged transport vessel) with a Dutch ensign. On the right on a spit of sand is a 'weyschuit' (a small open boat with a straight raking stern, usually rigged with a sprit), and behind, is a man-of-war, flying Dutch colours.
This picture was probably painted in the early 1660s in the van de Velde studio, possibly without Willem van de Velde's involvement. It could also be a late 17th or early 18th-century copy.