Freeze plastic toy dinos/sea creatures in water (Tupperware type containers, or balloons). Use food colouring for blue sea. These are good for the tough tray
Indoor treasure hunt, draw pictures of where to look for the next clue, or you read them aloud.
Find 1 silver thing, 2 blue, 3 green etc etc
Outdoor scavenger hunt - find a feather, pinecone, stone, she'll, yellow flower, twig, etc. Spot a bird, cat, red car, etc.
Play doh.
Painting
(Magic painting books)
Sticking - make Christmas cards?
Baking
Stick YouTube on and get dancing.
Hide and seek
Get him involved in cleaning - dusting, stripping beds , hoovering. Mine love it and it takes AGES.
After you've got the dinosaur/sea creatures filthy outside, they'll need a bath with lots of bubbles
Disco bath- glow sticks in the bath in the dark.