Why were the portuguese venturing into the atlantic ocean? they were in competition with spain to discover and conquer the most land in africa and the americas. having finally expelled the muslim moors from iberia, they sought to expand their borders as a means to protect their lands. they wanted to reach the sources of gold, ivory, and enslaved people that muslim merchants transported. they were convinced by prince henry the navigator, who wanted to put to use new tools and techniques for navigating great distance