His idea of a vacation was to travel to Cornwall to study hookworm in miners. Aldous Huxley, the novelist grandson of T. H. Huxley, who lived with the Haldanes for a time, parodied him, a touch mercilessly, as the scientist Edward Tantamount in the novel Point Counter Point.
去康沃尔研究矿工们的钩虫病算是他的假日。T.H.赫胥黎的孙子、小说家奥尔德斯·赫胥黎曾和霍尔丹夫妇一起生活过一段时间，有点残忍地以他为原型在小说《对立》中塑造了科学家爱德华·坦特芒特这个人物。

Haldane's gift to diving was to work out the rest intervals necessary to manage an ascent from the depths without getting the bends, but his interests ranged across the whole of physiology, from studying altitude sickness in climbers to the problems of heatstroke in desert regions. He had a particular interest in the effects of toxic gases on the human body. To understand more exactly how carbon monoxide leaks killed miners, he methodically poisoned himself, carefully taking and measuring his own blood samples the while. He quit only when he was on the verge of losing all muscle control and his blood saturation level had reached 56 percent—a level, as Trevor Norton notes in his entertaining history of diving, Stars Beneath the Sea, only fractionally removed from nearly certain lethality.
霍尔丹对潜水的贡献，在于计算出了从深处上升的过程中为避免得减压病所必须的休息间距。但是，他的兴趣涵盖生理学的整个领域，从研究登山运动员的高原病，到沙漠地区中暑的问题。他对有毒气体对人体的影响尤其有兴趣。为了更确切地了解泄露的一氧化碳如何夺走矿工的生命，他一面加大自己身体的中毒程度，一面仔细抽取并化验自己的血样。直到全部肌肉快要失去控制，血里的饱和度达到56%，他才煞手。特雷弗·诺顿在他趣味性很强的潜水史《海底明星》中指出，这种饱和度里送命只差分毫。
Haldane's son Jack, known to posterity as J.B.S., was a remarkable prodigy who took an interest in his father's work almost from infancy. At the age of three he was overheard demanding peevishly of his father, "But is it oxyhaemoglobin or carboxyhaemoglobin?"
后辈们称霍尔丹的儿子为J.B.S，他是个了不起的奇才，几乎从小对他父亲的工作很有兴趣。人们听说，他3岁的时候就生气地问他的父亲：“那不是氧化血红蛋白或羧基血红蛋白吗？”