With just one deep breath Mariam Shalan can reach depths of 50m. At only 17 years old, she holds the Egyptian National Record for 50m free diving in the category Constant Weight, and is the youngest professional female free diver in Saudi Arabia. 

Free diving is quite technical. Terms such as breathe up, lung packing and lung squeeze are just some terms used by free divers. 

I met Mariam at her home in Jeddah so she could explain this all to me.