SOUTH PADRE ISLAND, Texas — Beachgoers who happened to be on South Padre Island Monday night got an unexpected surprise: A blue glow in the waves caused by bioluminescence or "glowing algae."   

Witnesses said it started at dusk and lasted until about midnight. 

People travel all over the world to see the magic of bioluminescence and scratch it off their bucket list. The photo above is Maldives. It's pretty common in some places -- but not Texas.

Rosell Elizondo, 30, of Brownsville witnessed the glowing algae and said it was on his bucket list.

“We visit regularly. This is the first time I’ve seen this! I was in awe,” he said.

University of Texas – Rio Grande Valley’s Coastal Studies said the blue glow is caused by a reaction between bioluminescent planted-based plankton and the ocean. 

According to the Smithsonian, most deep-sea animals are bioluminescent to some extent, but the most common occurrence happens at the surface with small plankton called dinoflagellates. The glow is triggered by a physical disturbance, such as waves crashing. However, when the dinoflagellates bloom in dense layers at the surface of the ocean, they can be poisonous. This is called harmful algal blooms or, as we know it, “red tide.” 

UTRGV Coastal Studies said although it is rare, this event has happened before at the island. There aren’t usually many witnesses since it is only visible at night. UTRGV Coastal Studies says they don't know how long it will last but it will  phase out with the wind and tide. The group is currently scouring the beach for samples to research.