Head-Up Swimming
If an athlete swims with a head-up position, this will lead to the athlete curling their neck upwards, putting many shoulder and neck muscles in improper positions. Many masters swimmers and some age-group swimmers still use this head position, impairing their strength and putting their shoulder muscles at risk for injury.
Solution: Focus on swimming with your head down, try looking at the bottom of the pool or only slightly in forward. Invest in a snorkel and practice having the swimmer have the water line just above their hair line.
https://www.youtube.com/watch?v=v3tNh1and0U&index=1&list=PLSgfCwixt5PJgZanuA_OgPfA3zmU0kHUy