This phrase, as used in bills of lading, means only the natural accidents incident to river navigation , and does not embrace such as may be avoided by the exercise of that kill, judgment, or foresight which are demanded from persons in a particular occupation . 35 Mo. 213. It includes dangers arising from unknown reefs which have suddenly formed in the channel, and are not discoverable by care and skill. Hill v. Sturgeon. 35 Mo. 213, 86 Am. Dec. 149; Garrison v. Insurance Co.. 19 IIow. 312. 15 L. Ed. 650: Ilibernia Ins. Co. v. Transp. Oo