The chapter begins with the Professor eating breakfast at a Chinese restaurant. After breakfast, Mr. F and the Professor go to a "fine coral beach" in order to do some swimming. After the swim, the Professor starts asking Mr. F some questions about life on the island. One such question is about why the people live there at all.

"Why," I asked Mr. F., "do you people live here on top of this dormant volcano when with a handful of diamonds you could live a life of lavish ease and comfort in any other country?"

Mr. F gives a fairly lengthy answer, but ultimately, he says they live there because they are happy on the island. The Professor expresses his concern about living on a volcano that might explode in cataclysmic fashion. Mr. F then explains their escape plan and device. He describes a huge flying platform that is lifted aloft by balloon power.

"It's a flying platform, a huge platform big enough to take us all swiftly into the air within ten minutes of a warning from the mountain."

Much of the chapter after this point is Mr. F giving mathematical details about the size of the platform, the lifting strength of the balloons, and the mechanism by which all of the balloons get rapidly inflated with hydrogen. The chapter ends with Mr. F recommending that the Professor secure himself a parachute in case he ever has to flee the island on the giant platform.

In Chapter 9, the Professor, with seemingly unlimited time on his hands, begins to puzzle over the circumstances of the islanders of Krakatoa.  He queries his host, Mr. F, who obligingly provides answers to his questions.  The Professor's most perplexing question is how, despite the great wealth of the diamond minds, the citizens of Krakatoa can "live happily...under the constant threat of being blown sky high".  Mr. F. concedes that, having found such fabulous wealth, the islanders have become "slaves of (their) own piggishness...locked...in a diamond prison".  On the other hand, they have considered the dangers of their environment, and have devised an ingenious method of escape, if necessary.  The islanders have created a huge platform, large enough to accommodate every member of Krakatoa, which can be elevated "swiftly into the air" through the power of twenty enormous hydrogen-powered balloons.  In case of an ultimate emergency, each family will rush to the platform, and has already been drilled as to its responsibilities in making the contraption work.  There will be ample room for the Professor as well, should the platform need to be used; he will only have to request that Mrs. S make him a parachute, so that, like the others, he will be able to disembark from the platform when it has reached its destination (Chapter 9).