जलयान या पानी का जहाज़ (ship), पानी पर तैरते हुए गति करने में सक्षम एक बहुत बडा डिब्बा होता है। जलयान, नाव (बोट) से इस मामले में भिन्न भिन्न है कि जलयान, नाव की तुलना में बहुत बडे होते हैं।

A ship is a large vessel that travels the world's oceans and other navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally distinguished from boats, based on size, shape, load capacity and purpose. Ships have supported exploration, trade, warfare, migration, colonization, and science. Ship transport is responsible for the largest portion of world commerce.