Costigan, Christopher (1810–35), explorer, was third son of Sylvester Costigan, distiller, of Thomas St., Dublin, and Catherine Costigan (née Fitzsimons or Fitzmont), formerly of Toddstown, Co. Meath. He was educated at Clongowes Wood College (1819–26) and, for a period, at Maynooth, following the wishes of his dying father. In 1835, at the age of 25, he decided to explore the Dead Sea, but had neither the training nor the experience necessary for such an undertaking. His ignorance of nautical matters was compounded by a serious error of judgement in timing: travelling in August, when the heat was most intense. Together with a Maltese sailor he set out for the Dead Sea. Forced to transport their boat by camel after being caught in rapids travelling downstream, the travellers were at one point attacked by Arabs. Costigan unsheathed his sword; eroded by rust, it snapped at the hilt. The expedition was saved by their terrified horse: it bolted towards the Arabs, who fled fearing an attack.
Reaching the Dead Sea unharmed, Costigan launched his boat and for eight days attempted to measure the depth of the sea. A line of up to 175 fathoms (320 m) was used and it was discovered that the bottom was rocky and sandy in places, with possibly a deep spring at one point. The explorers spent most nights on shore, but remained at sea when threatened by marauding Arabs. During the day temperatures reached 95° F (35° C), and Costigan swam to remain cool. Disaster struck on the sixth day when their water supply was exhausted; some later accounts blamed the Maltese sailor for disposing of it to shorten the journey. The next day Costigan drank sea-water. On the eighth day, exhausted and severely ill, he was obliged to end his exploration and rest while his companion set out for help. The governor of Jerusalem sent aid and Costigan managed to reach Jericho, finding shelter at an Arab woman's house. On Friday 4 September a protestant missionary, the Rev. Nicolayson, arrived at Jericho and found Costigan lying in the open. There was no immediate improvement in his condition and they set out for Jerusalem, arriving at the Casa Nuova, a Franciscan hospice, the next day. Costigan made a partial recovery but his fever returned suddenly and he died, after receiving the sacraments from a catholic priest, on Monday 7 September 1835. He was buried at the Latin cemetery at Mount Sion. His mother erected a gravestone inscribed with a detailed account of his career and recording that he possessed a ‘modest and agreeable disposition’. In 1848 Lt. W. F. Lynch of the US Navy visited the area and named the extremity of the El Lisan peninsula, on the eastern side of the sea, ‘Point Costigan’ after the intrepid explorer.