Ed Harrison was born in Ireland in 1886, but was working in California by the early 20th century.

His ability to sustain long dives made him famous among passengers on the glass-bottomed boats of Catalina Island.

He once trained Sea Bass to swim to him and take food from his hand during his dives.

I found this postcard at an antique mall, but learned (from doing some research on his life) that the image was widely published and that many similar cards exist.

Although the postcard meets postal regulations, it was, primarily, a promotion and a souvenir of Catalina Island; it could not contain a personal message to recipients.

Most souvenir cards, like this one, were not mailed.

Interestingly, Ed Harrison died in 1926 after performing strenuous dives to find the body of Aimee Semple McPherson, the early tent evangelist and celebrity who disappeared that year. 

He was forty years old.

On-line, one can find many interesting tales from the life  of Ed Harrison.