SCIENCE FOR CHILDREN-Having already done this, it was a great addition for sand and sensory for even toddlers. Developmentally appropriate for children of all ages depending on what is added. Will absolutely do this again and again, the children loved it!!
Make an ocean bottle - fill a 1/3 of a plastic bottle with water, add blue food colouring, oil to fill the rest of the bottle, seashells, stones, plastic fishes & plastic beads. As the oil & water doesn't mix, the oil creates slow waves in the water when you turn it back & forth