What benefits did sea trading have over land trade routes?

The lack of safety and crossing great distances are considered as a plus factor in sea trading than overland trade routes. Using the sea lanes is much easier and faster than going through the traditional land routes, and also there is less restrictions, so even smugglers normally use the sea routes than the land routes.  

There are two physical types of trade routes: overland and nautical. An overland route connects multiple points by land, and originally was traversed by caravans, or merchants who traveled in groups for convenience and protection. With the invention of the automobile, highways, and pipelines, the need for caravans is largely obsolete, though some caravans still exist along trade routes in less-developed areas of the world. A nautical route is traversed by sea and tends to involve the use of large ships that carry significant quantities of goods, often over vast distances. Nautical routes are the most common and least expensive method of transporting goods in the modern day.  

Maritime trade along the Spice Route became prominent during the Middle Ages, when nations resorted to military means for control of this influential route. During the Middle Ages, organizations such as the Hanseatic League, aimed at protecting interests of the merchants, and trade became increasingly prominent.

a. the moon was locked into orbit by the earths gravity as it was passing by and capture hypothesis i think