The Uluburun wreck (discussed in this month's Discover and Create blog) was littered with hundreds of copper ingots - metal blocks like in the image below. Why would Bronze Age sailors have carried so many of these blocks with them? Let's find out!
Over 300 of these copper ingots were found stacked in rows at the bottom of the Uluburun ship, each one weighing nearly 30 kilograms. That makes a total of 9,000 kilograms, which can't have been much help when the ship started sinking!
To answer the very reasonable question of why you would bring so many seemingly pointless, heavy metal slabs with you, when your aim is to stay above water, we have to think about the time period in which the ship sank: the Bronze Age. Dating from about 3300 BCE to 1200 BCE, this period of history was special because of how popular bronze was for making tools, weapons, armour, jewellery, and many other objects. Bronze is not a naturally occurring metal, but is made from mixing tin with... copper! So, now it seems clear why heavy blocks of copper might have been useful!
If they hadn't sunk, the sailors of the Uluburun ship would have sold these ingots to manufacturers and metal workers, who would have used them to make bronze. You can see some ancient bronze artefacts in the Gods, Myths, and Mortals exhibition at the Hellenic Museum!