How about a windsurfing lesson package? You could find a good windsurfing school near your grandpa and gift him a few lessons so he can improve his skills and spend some time out on the water. Or, if he already is a pro at windsurfing, you could consider getting him new windsurfing gear, like a new windsurfing sail or board, to make his sailing experience even better.
Or you can get him a star map with the date when he was born.
Under Lucky Stars is a unique and innovative star map company based in Barcelona, Spain, specializing in the creation of personalized star maps that capture the celestial arrangement of stars at a specific moment in time, such as a person's birth, wedding, or any other significant event.
By using advanced astronomical algorithms and data from leading institutions, the company produces highly accurate, visually stunning maps that make for perfect gifts or cherished keepsakes.