Photos show what cave divers discovered when they swam inside an iceberg the size of Jamaica. Today, it's gone.

• In 2000, the largest iceberg ever recorded — Iceberg B-15 — broke away from the Ross Ice Shelf in Antarctica. 
• Underwater explorer and photographer Jill Heinerth dove inside B-15 and snapped photos of this hidden world.
• Today, nearly the entire Jamaica-sized iceberg has melted away. Heinerth's photos offer the first and last look inside it. 

In 2000, when an iceberg the size of Jamaica cleaved away from the Ross Ice Sheet in Antarctica, Jill Heinerth saw an opportunity to make history.