Play boardgames.
Get them to invent boardgames then play them as a family.
Beach for rock pool, sandcastles, swimming, beach combing, dolphin watching.
Swim in a lake and a river.
Go to the woods, look for birds, insects, funny-shaped sticks, pine cones nibbles by squirrels.
Find a stream, make a damn with mates, Pooh sticks, stepping stones.
I haven't done 1/4 of the things listed so far: Florida, Lapland, northern lights, Eiffel Tower, Harry Potter world. Not in my lifetime, not in my child's.
Things I did as a child that I have carried with me:
Love of and respect for nature.
I can see, I can cook, I can change a plug, do DIY, paint, wallpaper, sand, use tools with confidence.
One thing I'd add to this list is make sure your child learns a foreign language, then they can make their own foreign adventures.