One of the 40s 4 40 challenges I set myself was to swim 40 metres underwater. I would do this with no fins; this is defined as Dynamic No Fins (DNF) by the International Association for Development of Apnea (AIDA).

I have been able to swim 25 metres under under water since I was a child. Nonetheless, turning around and doing more remained unfathomable to me.

I found myself taking a tape measure to the pool to measure how far 40 metres was and putting a submersible marker down so that i knew when i had reached 40 metres. I soon got tired of this hassle and so decided that I would simply aim to swim 50 metres or 2 lengths of a 25 metre pool.

Here is one of my earlier attempts:

I managed to do this and subsequently replicated it to ensure it wasn’t a fluke!

I became concerned that I was completing over 40 metres by pushing off the wall twice. For example, in a 25 metre pool you can push off the side at the start and again around half-way through; in a 50 metre pool, you can only push off once.

There happens to be a large pool near where I live and so it naturally became an aspiration of mine to see if I could swim the full pool length underwater.

I’ve done quite a bit of scuba and free diving in the recent past and have learnt a lot. Of the greatest importance is to relax, followed by having strong but smooth actions and a hydrodynamic position that allows you to glide. These things enable you not to build up too much resistance in the water and to limit carbon dioxide build up and thus, the desire to breathe.

To that end, I must thank my talented friends who gave up their own time to help me achieve this safely, Mirka, Amr, Shohreh, Mike and Zak who helped me to learn a real appreciation of apnea and some of the techniques required to make this possible.

Pictures or it didn’t happen: