"On the Beach" is the 178th episode of the NBC drama series ER. It chronicled the last days of Dr. Mark Greene as he died from a brain tumor and marked the final performance of Anthony Edwards until his return in a flashback during a Season 15 episode.
Synopsis
Dr. Greene has resigned his fate and decided to forgo his remaining chemotherapy treatments, choosing to spend his remaining days in Hawaii with Elizabeth and Rachel. He creates a "bucket list", detailing everything he wants to do before he dies, with one of the items being to fix Rachel.
As his health deteriorates, Greene makes amends with Rachel and gives her some last advice: "be generous with your time, with your love, with your life." Rachel puts a pair of headphones on him and he listens to "Over the Rainbow" as we see him walk through the empty hallways of the ER (his entrance into heaven). The next morning, Elizabeth discovers that Mark has died.