find a nice big 3d picture frame and go for a scavenger hunt with oscar collect some sand, shells sea-weed, driftwood etc and maybe a few items from a gift shop with a naughtical theme and have fun creating an art work together or if you could find a double fame include a picture of Oscar or both of you on your adventure providing a keepsake to remember the day by.(actually a nice b&w pic of Oscar picking up a treasure off the beach would be sweet)