Field Trip: Aquarium
Try Something New: Get two pairs of tongs and use them to pick up and move things like a crab
Library: Undersea books
Crafts: submarine out of plastic bottle, paper plate aquarium
Kids Cook: submarine sandwiches
Rainy Day Fun: Give each kid a bowl of water, with a tablespoon of oil added to the water, and a spoon. Tell the kids to scoop out the oil with the spoon. This is a great lesson in water conservation. They will find it impossible to get all the oil out. You can let them use a paper towel at the end, but they will find it takes away much more water than oil.
Outdoor: Beach themed scavenger hunt, make a list of things that can be easily found throughout the week, give each kid a sand pail to collect the goodies in. If you don't live near the beach, then you can scatter bath toys around the yard and have them hunt for them.
Movie: Little Mermaid or Finding Nemo
Craft Challenge: Sea shell critter, get a bag of sea shells from the craft store and how many different sea shell creatures you can make
Weekly Challenge: Who can crab walk the farthest