If you’re in the market to understand why natural places have such weird names, it often helps to crack open a history book and see who first “discovered” it. In the case of Manly Beach, Australia, it was Captain Arthur Phillip. Upon seeing the indigenous people who called the area home, Phillip intimated that their “confidence and manly behaviour made [him] give the name of Manly Cove to this place”. Phillip later became the first Governor of New South Wales and also the founder of what would eventually become Sydney.
It should be noted that Phillip maintained close relations with aboriginals upon his arrival, saying that they should never be slain and that colonists should not retaliate against non-fatal spearing. That, however, changed when his gamekeeper had been killed by Aboriginals and Phillip had six of them put to death.