For my little boys birthday we decided to have an under the sea party. He was turning 2 and I found party plates at a local store that were so cute. I used this as my inspiration. For invitations I went to a local teacher store and bought a notepad shaped like a crab at the beach.  I backed each sheet with cardstock for stability and added the information. I also had some stamps of seaweed and fish so I decorated the back with this also.  I then laminated the crab.  (I had access to a laminating machine at work.) I then put the crab in a ziploc bag and added blue hair gel (which I purchased a huge container of at .99 cents always).  I put fish and underwater themed confetti in the bag and sealed the bag with super glue.  It looked like a crab in the ocean.  I purchased some bright colored envelopes at Office Max to put them in.  I handed out the invitations since they were heavy and I was afraid they would bust.  Everyone loved them.  I had the party in my back yard. For entertainment, I went to a local dollar store and purchased some one ring pools. In one I put sand with toys, in another I put bubbles and wands. In another I put water balloons. I also had some bigger activity pools for the kids to swim in.  The only Art we did since they were 2 was edible sand art. I used stage 1 baby food jars and cleaned them very well.  I spray painted the lids gold.  Then using neon pixie sticks they layed their "sand" in the jars.  For decorations I purchased underwater stuff from local dollar stores, party supply stores, Big Lots, and Oriental Trading.  I also made posters from poster board, scrapbook paper, and stamps that had all kinds of beach sayings like Hang Loose, Beware of Sharks, No LifeGuard on Duty, etc. I borrowed a screened outdoor tent from my sister.  We made a sign saying the snack shack and made it look like a hut using palm trees and rafia. For food, We had gold fish, blue jello with gummy fish made in fish bowls.  Octopus on seaweed.( Hot dogs cut to have 8 legs and boiled to make them curl up sitting on noodles boiled with green food coloring).  I also made chocolate crab and fish suckers from candy molds.  I served the food from fish bowls and sand buckets. For drinks I bought Hawaiian Punch Cans, Koolaid Jammers, and waters and put them in a one ring pool.  I bought an inflatable palm tree from oriental trading and put in the center. Then I iced down the drinks. For the cake,  I baked a cake and cut it up into pieces. I layered the cake and vanilla pudding in a sand bucket and topped it with crumbled gram crackers.(I got this idea from FamilyFun.com)  To add to it, I made sea shells from candy molds and chocolate. Instead of loot bags, I purchased mini-sand buckets from oriental trading. They came with the sand bucket, 3pc. sand tool set, a fish clapper, sunglasses, & fish squirter. I added some little bubbles to them (which I added a label that said thanks for coming to my party with a beach scene on them that I made on the computer), and a starfish blow.  Everything was so cute. It was very inexpensive since I started planning ahead and bought alot of things at local dollar stores. I also made alot of things myself which took time but cut cost.  There is also plenty of great ideas on preschool education websites to help with decorations, food ideas and activities.