A World of Happiness

Plot: the protagonist decides to make himself a small boat to be able to find solace to his ailments in the sea, but receives a letter in which he was told that he was hired at the bank. In his new job he is very bad, and for that pretends to be sick to take a vacation in the Sahara. After many misadventures, which threatens the life, is able to return and resume work. But yet another insult suffered by superiors, convince him to resign, take the small boat and venture out into the sea.
Here he meets a mermaid who invites him in her amazing underwater world, but ..