To locate your kayak's serial number look at the right (starboard) side on the back (stern) of the boat on the outside of the hull. Most, but not all boats, have a recessed area here. Your serial number will always be in this area. Additionally, the serial number may be on the side of the left (port) thigh brace, either on the side facing into the center of the cockpit, or occasionally on the side facing away towards the hull.

The side location.

The thigh brace location.

The serial number consists of alphanumaric characters engraved into the recess.

European made boats will bear a five digit serial number, preceded by 'UK', eg UK12345, and are engraved into the recess on the hull at the back of the boat.

American made boats will bear a twelve character alphanumeric, eg WEMELA29A909. ('WEM' is the US coast guard manufacturer identification code. The last four characters (A909) represent the month your boat was made (A for January, B for February); the model year (in this case 2009); and the year your boat was made (09 means molded in 2009).