I really like this educational program called Adventures of Scuba Jack because of it's rich educational content, made FUN! 

From their website:

"The Adventures of Scuba Jack is an educational program designed for preschool children by a successful preschool educator. Each episode brings children into the simulated preschool classroom of Majestic Harbor School. From there, they are taken on exciting adventures with Scuba Jack and his friends.  On these adventures they learn about the places and creatures that were introduced by their preschool teacher, Ms. Beth. Now your children can follow along with Ms. Beth, Scuba Jack and all their friends as they discover and learn about the world around them."