Until the 20th century, boats were propelled by oar and sail (see Sailing), just as they had been since ancient times. Paddles and poles (for pushing against the bottom of the waterway) were variations on the oar suitable for small craft. The rapid rise of the steam engine to dominance among ships did not affect boats until the late 19th century, when steam engines and boilers had become compact enough to fit into a small hull. The age of steam-propelled boats was brief, however, for the advent of commercial internal-combustion engines came within a few years of boat-size steam machinery. By the late 20th century, the internal-combustion engine, either in diesel or spark-ignition (gasoline) form, had become almost universal in boat propulsion, save for sail, oar, and paddle that survive with many types of recreational boats.
Motorboats are popular recreational vehicles, present on many lakes and oceans throughout the world. Inboard-outboard (I/O) motorboats such as this Donzi Z-25 are capable of reaching speeds of 80 kilometers per hour (50 miles per hour).