velopharyngeal closure to keep water out of your nose

Ok so I'm pretty sure most people do this instinctively or whatever - I was not one of them and I hope this finds the right person. I've never been able to swim without holding my nose under water. I've since learned that there is actually a muscle that swimmers use to keep water out.

Basically exhale a bit and swallow at the same time, hold the position of your tongue at the start of the swallow. If you are doing it right you physically will not be able to inhale through your nose until you release the position. Apparently humming and making a "k" sound also puts you in the right position.