Crusaders made their way to the Holy Land by whatever means they could. Many went by land, and many went by sea. The Crusaders of the First Crusade, which began in 1095, went mostly by land to reach Jerusalem. Some of the wealthier knights did travel part of the way by boat down the Danube River, but mostly they went over land in large caravans. This was slow going, and it took these crusaders nearly a year to reach the Holy Land on a journey of over two thousand miles.
During the following Crusades, many crusaders still traveled over land. However, a number of lucrative maritime transportation enterprises developed to ferry Crusaders by sea to the Holy Land. Most of these were based out of Italy, particularly in the city-states of Venice and Genoa. This saved the Crusaders a lot of time, as this journey by sea took weeks instead of months.
The Second Crusade involved a combination of land and sea routes. Most Crusaders went over land to Constantinople. There, they split in two, with some of the forces marching across Anatolia and others following the coast in ships until they reached the port of Acre.
The Third Crusade was the first to go almost entirely by sea. This involved two fleets, one leaving from Genoa and the other, under the command of King Richard of England, leaving from England and traveling by way of Marseille.
The Seventh Crusade, led by King Louis IX of France, involved a huge fleet of thirty-six ships that sailed from southern France to the Holy Land by way of Cyprus. This is considered the largest single Crusader fleet.
Most of the later Crusades relied almost entirely on ocean-going transportation. This solved the huge logistical mess that was involved in supplying, feeding, and housing large armies on the march. By traveling by sea, Crusaders arrived sooner at their destination without the need of the large and complicated supply lines that would otherwise be necessary to support them on land journeys.