Many serious childhood diseases like meningitis and polio left people partially paralyzed and water exercises were a common physical therapy, especially for poorer people who couldn't afford specialized equipment or personal doctors. Colombo's brothers basically carried him to the ocean, through the water, and back home every day to see if they could get him strong enough to walk again, and luckily it worked.

I know the feeling of not wanting to click on links, so here's the answer to your other question:

>Galveston was a tricky area for all levels of swimmers. On the Gulf side of the island the water is treacherous. There are sandbars and places where the ocean floor drops away unexpectedly. The riptides are a constant issue, pulling under experienced and inexperienced swimmers alike.
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>The peril was increased because in the early 1900s, few people learned water safety. The first swimming programs in the U.S. began in 1912 (see Wilbert E. Longfellow), and the programs were slow to spread throughout the country. Those who came to Galveston for vacation often did not know how to swim, because few towns and cities had public access to pools.
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>Yet summers were hot, and there was no air conditioning until the late 1920s-1930s. Many traveled to Galveston to enjoy the cooling ocean breezes, and of course, they went into the water.
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>Take unpredictable currents and mix in crowds of people who don’t know how to swim (or how to swim well), and Galveston had the makings of daily disaster.

The other thing the article doesn't mention is that the few pools available almost always banned non-White swimmers, so it was especially hard for non-White people to learn to swim in a safe setting. In his biography, Colombo said he tried to pay equal attention to swimmers of all races and ethnicities, which I guess other lifeguards weren't doing at the time (yikes). This would have also increased the numbers of potential drowning victims he noticed and saved.