The expression ” dangers of the sea ” means those accidents peculiar to navigation that are of an extraordinary nature. or arise from irresistible force or overwhelming power, which cannot be guarded against by the ordinary exertions of human skill and prudence. Walker v. Western Transp. Co.. 3 Wall. 150. 18 L. Ed. 172: The Portsmouth. 9 Wall. 682. 19 L. Ed. 754: Hihernia Ins. Co. v. Transp. Co., 120 TT. S. 160. 7 Sup. Ct. 550. 30 L Ed. 021; Hill v. Sturgeon, 28 Mo. 327.