In Patrick O'Brian's "Desolation Island," Stephen is given a small canvas boat, with the intention that he would be safe in the calm sea while using two inflated bladders from a sea elephant. However, a mishap occurs when he mistakenly gets entangled with his umbrella, leading to a realization that the bladders only support his thin legs. This unfortunate incident highlights the inadequacies of the safety measures intended for him, as his stability in the water relies heavily on the presence of Babbington's Newfoundland dog.

As a result of this incident, a decision is made to prohibit Stephen from venturing out alone. This reflects a larger theme in the story regarding the fragility of human safety and the unforeseen challenges that can arise even in seemingly calm situations. The combination of humor and seriousness in this passage illustrates the precarities faced by the characters, and adds depth to their experiences within the narrative.