The Halmahera Sea (click here to sea map) is a biodiverse regional sea located in eastern Indonesia, nestled between the islands of Halmahera to the west, New Guinea (Papua) to the east, and the Sulawesi (Celebes) Sea to the north. It connects to the Pacific Ocean via the Molucca Sea and is part of the famed Coral Triangle, home to some of the world’s richest marine ecosystems.
In this guide, we will explore:
- Exact location & bordering regions
- Depth, geography, and marine significance
- Why it matters for biodiversity and trade
- How it connects to the Pacific Ocean
Where is the Halmahera Sea Located?
The Halmahera Sea lies within Indonesian waters, centered around 0°30′N latitude and 128°00′E longitude. Key bordering islands include:
- Halmahera (North Maluku) – Western boundary
- Waigeo and Gebe Islands (West Papua) – Eastern edge
- Molucca Sea (north) & Seram Sea (south) – Major connecting waterways
This sea is part of Indonesia’s North Maluku and West Papua provinces, making it a crucial maritime zone for local fisheries and navigation.
What Countries Border the Halmahera Sea?
Unlike shared seas like the South China Sea, the Halmahera Sea is entirely within Indonesia’s territory. The nearest foreign waters are:
- Papua New Guinea (east)
- The Philippines (north)
Indonesia maintains full sovereignty over this region, regulating fishing and shipping activities.
How Deep is the Halmahera Sea?
- Average depth: ~1,000 meters (3,280 ft)
- Maximum depth: ~2,039 meters (6,690 ft)
- Compared to nearby seas:
- Banda Sea (deeper, max ~7,400 m)
- Ceram Sea (shallower, ~1,000 m avg.)
Its deep basins support unique marine life, including rare deep-sea corals.
Why is the Halmahera Sea Important?
A. Marine Biodiversity Hotspot
- Part of the Coral Triangle (highest marine species diversity on Earth)
- Home to endangered sea turtles, reef sharks, and manta rays
- Key breeding ground for tuna and other pelagic fish
B. Economic & Strategic Value
- Local fishing industry sustains Indonesian coastal communities
- Potential shipping route between the Pacific and Indian Oceans
- Growing eco-tourism & diving opportunities
Is the Halmahera Sea Part of the Pacific Ocean?
Yes, the Halmahera Sea is a marginal sea of the Pacific Ocean, connected via:
- The Molucca Passage (north)
- The Seram Sea (south)
It plays a role in Pacific-Indian Ocean water exchange, influencing regional climate patterns.
Interesting Facts About the Halmahera Sea
Did you know? The Halmahera Sea is full of surprises! Here are some fascinating titbits:
- Underwater Volcanoes: The seafloor has active hydrothermal vents, supporting unique ecosystems that thrive in extreme heat.
- WWII Shipwrecks: Several sunken warships from World War II lie in its depths, attracting divers and historians.
- Rare Marine Species: It is one of the few places where the endangered dugong (sea cow) and giant clams can still be found.
- Bird’s Head Seascape Connection: Part of the larger Bird’s Head Seascape, one of the most biodiverse marine regions on Earth.
These hidden wonders make the Halmahera Sea a true gem of Indonesia’s underwater world!
