I was studying abroad in Costa Rica and I came across a pair of damselflies in tandem. I followed them to observe their mating behavior. While in tandem, the female submerged completely underwater for 45 minutes, laying eggs along the vegetation. I have searched books and documents and haven't found this type of behavior documented anywhere. Doesn't anybody know if this is a regular occurrence??

Yes, its quite normal.
I had seen a male holding the female even under water for some time. But before he was dragged completely underwater, he flew up and circled around the female until she surfaced. He then picked her up from the water and carried away to dry.
They are so small, but so amazing...