Jerónimo de Ayanz y Beaumont (1553 – March 23, 1613 AD) was a Spanish soldier, painter, astronomer, musician and inventor.
He was born in Guendulain (Navarre).
He is best remembered for the invention of a steam-powered water pump for draining mines, for which he was granted a patent by the Spanish monarchy in 1606.
He also improved scientific equipment, developed windmills and new types of furnaces for metallurgy and industrial, military and household use. He invented a bell-like diving suit and even designed a submarine. He died from a serious illness in Madrid, in 1613.