How do Austronesian languages use mountain-sea directions instead of north and south?

Many Austronesian languages utilize a system of spatial orientation based on a land-sea axis rather than cardinal directions like north and south, which often only appeared after European contact.1

This orientation system relies on the physical geography of the speaker's environment, specifically the relationship between the mountains and the sea. Examples of this include:1

• Thao (central Taiwan): Uses tana-saya for "uphill, toward the mountains" and tana-raus for "downhill, toward the sea".1
• Hawaiian: Uses mauka for "toward the mountains" and makai for "toward the sea".1

This land-sea axis is widespread among Austronesian-speaking peoples, providing a consistent way to navigate and describe location relative to the landscape.1