How did you celebrate your 50th?

 
A friend came around this evening that I hadn’t seen for some time, and we got to talk about scuba diving. She is about to get her Masters allowing her to dive to 40 metres.
 
That’s when she mentioned on her 50th birthday she celebrated with scuba diving in Mauritius. Today’s photo is from that dive. ( See extra for one of the fish she saw.)
How did you celebrate your 50th?  Or any big 'O' birthday?
Personally, I have always chosen to ignore them but I am full of admiration for those who give themselves  a big challenge to mark the occasion.