I love working with older adults who have recently retired and have chosen to take up swimming as way to maintain their cardiovascular health. As part of a long set, I encourage my clients to use a snorkel as it limits the need to take breaths through rotary (side) or rhythmic (alternating sides) breathing. It also slows them down so they can concentrate of their technique and build the right muscle memory.
Swimming long yardage with poor technique will only injure the body, and potentially damage the spine. I will talk in an upcoming blog post about the head up vs. head down position that can be confusing to some nbeginning swimmers. Here my client is working is way through a middle distance set with a Finis snorkel. He is working on his arm movement, getting the highest elbow possible for his ability.