China Hong Kong Submarine Cable Overview | Generated by AI
Question: How many submarine cables connect mainland China directly to Hong Kong? Is it 7 cables? What are they, and which are the shortest?
Answer:
Submarine Cables Connecting Mainland China to Hong Kong
Your estimate of 7 is a reasonable approximation, but the actual picture is a bit more nuanced. The answer depends on whether you count cables that directly and exclusively link mainland China to Hong Kong, or cables that touch both mainland China and Hong Kong as part of a larger multi-country network.
Overall Context: Hong Kong’s Cable Connections
As of July 2025, Hong Kong has twelve international submarine cable systems in service: AAE-1, AAG, ADC, APCN-2, APG, ASE, EAC-C2C, FNAL/RNAL, H2HE, SJC, SJC2, and TGN-IA. Of these, several have landing points on both the Hong Kong side and the mainland China side.
Cables With Landing Points in Both Mainland China AND Hong Kong
The key cables that touch both territories include:
| Cable | Full Name | Mainland China Landing | Length / Notes |
|---|---|---|---|
| H2HE | Hainan to Hong Kong Express | Hainan + Guangdong | 675 km — shortest, most direct |
| APCN-2 | Asia Pacific Cable Network 2 | Chongming, Shantou | ~19,000 km total (ring) |
| APG | Asia Pacific Gateway | Multiple mainland points | Multi-country |
| EAC-C2C | East Asia Crossing / City-to-City | Shanghai, other cities | ~36,800 km total network |
| SJC | South-East Asia Japan Cable | Shantou | Multi-country |
| ADC | Asia Direct Cable | Guangdong Province | ~9,400 km total |
| SEA-H2X | South-East Asia Hainan-Hongkong Express | Hainan | ~6,000 km (under commissioning ~2025) |
So roughly 7 cables do indeed have landing points in both mainland China and Hong Kong, which is why your instinct was in the right ballpark.
The Shortest: H2HE
The Hainan to Hong Kong Express (H2HE) is a 675 km submarine cable system connecting Hong Kong SAR and Hainan Province, Mainland China, with a branch to Guangdong Province. It is by far the shortest and most direct cable between the two territories.
H2HE is also notable for being the world’s first 16-fibre-pair repeatered submarine cable system, achieving a system capacity of over 300 Tbps, which is sufficient to transmit 57,000 high-definition movies every second.
H2HE was put into service in September 2021 and is operated by China Mobile.
Key Details on Other Notable Cables
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ADC (Asia Direct Cable): ADC is a 9,400-kilometre submarine cable connecting Hong Kong with mainland China, Japan, the Philippines, Singapore, Thailand, and Vietnam. With eight pairs of optical fibres, it carries traffic above 140 Tbps.
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APCN-2: The 19,000 km-long APCN-2 cable system is built in a self-healing ring configuration, connecting Hong Kong to Chongming and Shantou in mainland China, along with other Asia-Pacific countries.
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EAC-C2C: The EAC-C2C network spans 36,800 km total, with 17 cable landing stations covering Japan, Korea, China, Taiwan, Hong Kong, the Philippines, and Singapore.
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SEA-H2X (newest): The SEA-H2X cable connects Hong Kong SAR, Hainan China, the Philippines, Thailand, and Singapore, with a design capacity of 200 Tbps across 8 fiber pairs, and was targeted to be ready for service by end of 2025.
Summary
- Your count of ~7 is essentially correct for cables that have landing stations in both mainland China and Hong Kong.
- Shortest cable: H2HE at 675 km, directly linking Hainan Province and Guangdong to Hong Kong.
- Most of the other cables are multi-country regional or international systems that happen to connect both territories as part of a larger network, with total lengths ranging from ~6,000 km to over 36,000 km.
References:
- Hong Kong - Submarine Networks (October 2025)
- H2HE - Submarine Networks
- OFCA Hong Kong Submarine Cables (July 2025)
- SEA-H2X - Submarine Networks
- ADC Landing Hong Kong - PR Newswire
- EAC-C2C - Submarine Networks