Azerbaijan, Kazakhstan, and the Empty Caspian Seafloor

The Caspian Sea is the largest enclosed body of water on Earth. It is bordered by five countries — Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan — and at its narrowest it is only about 380 kilometers wide. On a clear day from the shore near Baku, you cannot see Kazakhstan. On the ocean floor below, you cannot see a fiber.

On 23 April 2026, we ran traceroutes in both directions between Kazakhstan and Azerbaijan — from five Kazakh probes on five different ASNs toward the main Azerbaijani international gateway, and from four Azerbaijani probes toward the Kazakh government's e-services IP. Nine probes, nine paths. Not one of them crossed the Caspian. Every single packet that left Almaty for Baku, and every single packet that left Baku for Almaty, traveled through Russia.

This is not because the Caspian is too wide. It is because, until the end of 2026, no submarine cable has ever been laid on its floor.

The Empty Sea

Five countries touch the Caspian's shoreline. Roughly 270 million people live in the broader hinterland of those shores. By submarine-cable standards, the Caspian is a small body of water: less than half the width of the Baltic at its narrow point, a quarter of the Mediterranean. The Mediterranean has more than thirty subsea cables on its floor. The Baltic has more than twenty. The Caribbean, which covers only a slightly larger area than the Caspian, has over thirty.

The Caspian has zero.

Not "few." Not "one or two old ones." Zero. Until AzerTelecom and Kazakhtelecom complete the Trans-Caspian Fiber Optic Cable Line later this year, there is no submarine fiber on the Caspian seabed at all. The result is the anomaly at the center of this piece: five neighbors whose internet traffic to each other routes around, rather than across, the sea that separates them.

Why the Sea Floor Stayed Empty

Three obstacles kept the Caspian cable-free for three decades of the commercial internet.

The first is legal. The Caspian's status under international law was disputed from the dissolution of the Soviet Union until the Convention on the Legal Status of the Caspian Sea was signed by all five littoral states in August 2018. Before that convention, no one knew whose jurisdiction a piece of seabed actually fell under, or which five governments had to approve a cable crossing it. There was no framework for permits, no precedent for environmental review, no authority that could even receive an application.

The second is logistical. A submarine cable is laid by specialized cable ships of a size that cannot fit through any connecting waterway to the Caspian except the Volga-Don Canal. That canal is narrow, shallow-draft, controlled by Russia, and — since 2022 — subject to sanctions regimes that make it close to unusable by most Western cable-laying operators and their insurers. Moving a vessel like Nexans' Aurora or ASN's Ile de Brehat through Volga-Don to lay a cable across the Caspian is not, in practice, an option. Any cable crossing the Caspian must be laid by equipment built, assembled, or adapted inside one of the littoral countries — a significant constraint on what the industry could even promise.

The third is political. Of the five shore countries, three (Russia, Iran, and Turkmenistan) have no commercial interest in competing with existing terrestrial transit monopolies that happen to earn substantial transit revenue from east-west data flows. For Russia, every Kazakh-to-Azerbaijani packet that travels through Moscow is a small stream of Russian transit revenue — and, for Moscow, an implicit sovereignty over the region's connectivity. A direct submarine cable between Aktau and Sumgayit is, among other things, a business loss.

The Russian Detour, Measured

Our Kazakh measurements ran from five probes on five distinct Kazakh autonomous systems, chosen to represent both the national incumbent and the independent operator ecosystem:

Four of the five traces transit Rostelecom (AS12389) or an adjacent Russian backbone — 195.208.208.79, 195.208.210.217 appear repeatedly as the last Russian-territory hops before the path exits into Delta Telecom's Baku network. The fifth, run from a Kazakhtelecom-hosted probe, drops into hidden hops after leaving Kazakhstan's domestic network — but its 170-millisecond round-trip time is inconsistent with any direct regional path and is consistent with a long European detour through a Kazakhtelecom international transit arrangement.

The reverse direction — four Azerbaijani probes measuring toward the Kazakh government's e-services endpoint at egov.kz — shows the same detour in a different Russian operator:

Three of the four Azerbaijani probes cross the Russian MegaFon backbone (AS31133). One crosses the Russian transit carrier RetnNet (AS57304). The path Azerbaijan → Kazakhstan, in April 2026, is Azerbaijan → Russia → Kazakhstan.

There is a subtle asymmetry. Kazakh-originated traffic favors Rostelecom (Russia's state fixed-line incumbent). Azerbaijani-originated traffic favors MegaFon (Russia's second-largest mobile/fixed operator). This reflects two different peering relationships that happened to form with two different Russian operators — but the net effect on the user is identical: every packet between the two countries crosses a third country that is not only non-neutral, but is an active political and commercial competitor to both.

A 380-kilometer trip across a sea becomes, on the wire, a six-to-eight-thousand-kilometer detour through Moscow, Novosibirsk, Frankfurt, or a combination of the three, every time.

The Iran Asymmetry

One month ago, we measured international routing into Turkmenistan and found that Iran — the neighbor directly south of Turkmenistan — reaches it by routing through Azerbaijan. There is a direct Iran-to-Azerbaijan peering: Iranian ISP Mobin Net (AS58224) reaches Delta Telecom's Baku gateway at about 96 milliseconds on a land route through Astara and the Baku metropolitan ring. When we re-measured Iranian probes into Azerbaijan for this piece, the result was unchanged.

Azerbaijan peers directly with Iran. Azerbaijan peers directly with Turkey (98-106 ms, Kars-to-Baku). Azerbaijan peers directly with Georgia (135 ms via Tbilisi). Azerbaijan does not, in any routable path we can find, peer directly with Kazakhstan — despite being its only east-west sea crossing neighbor.

The reason is geometry. Iran, Turkey, and Georgia all share a land border with Azerbaijan. Kazakhstan does not. Everything short of a submarine cable has to travel through a third country — and that third country, every time, is Russia.

The Cable Being Laid

The Trans-Caspian Fiber Optic Cable Line (TCFO) is, in the oldest sense of the word, infrastructure. A single submarine cable — 380 to 400 kilometers long — will run along the Caspian seabed from Sumgayit, Azerbaijan (a coastal industrial town north of Baku) to Aktau, Kazakhstan (Kazakhstan's main Caspian port city). It will carry up to 400 terabits per second — not the largest capacity in the industry, but a step-change for a region whose entire east-west capacity today runs through Russia.

The partners are AzerTelecom (NEQSOL Holding subsidiary, backbone carrier of Azerbaijan, announcing prefixes under AS196925) and Kazakhtelecom (the Kazakh state incumbent, AS9198 and AS50482). Route engineering and supervision are by Pioneer Consulting, the Boston-based submarine consultancy that has worked on the project since January 2024.

The project was launched in late 2018 and was originally planned to be in service by the end of 2024. Every milestone slipped. The March 2025 construction agreement was followed by a desktop study finishing in June 2025, marine surveys in August 2025, and deepwater cable installation through the winter of 2025-2026. Commissioning is now planned for Q3 2026. Full completion by the end of 2026.

The cable has a Phase 2: a similar subsea cable between Azerbaijan and Turkmenistan, crossing the Caspian from Sumgayit to a yet-undisclosed landing near Turkmenbashi. Phase 2 has no firm commissioning date. If it happens, the topology we described in our Turkmenistan piece — two foreign gateways, three IP addresses, zero internal vantage points — stops being a strictly landlocked-via-neighbors story and gains a second foreign submarine door. That is a separate article. For now, Phase 2 is a line on a map.

What Q3 2026 Changes

The submarine portion of a direct Aktau-Sumgayit link is about 380 kilometers of undersea fiber. At the speed of light in glass, and accounting for round-trip, that is a theoretical RTT floor of roughly 7.6 milliseconds. With terrestrial backhaul from Almaty to Aktau (about 2,000 kilometers overland, ~20 milliseconds) and from Sumgayit to Baku (under 50 kilometers, ~1 millisecond), the realistic end-to-end RTT between the two countries' main commercial hubs drops from the current 82-170 milliseconds via Russia to somewhere around 25-35 milliseconds.

A four-to-five-times latency improvement is the headline. The more strategic change is about independence. For the first time since the commercial internet reached the region in the 1990s, Kazakhstan and Azerbaijan will have a direct digital link that does not ask permission of a third country. Digital Silk Way — the broader corridor that will eventually connect Europe (via Italy's Sparkle) through Georgia, Azerbaijan, the Caspian, Kazakhstan, and onward to China — stops being contingent on Russian cooperation for one of its critical segments.

It is also not a coincidence that this cable, promised for 2024 and delivered in 2026, gained institutional urgency after February 2022. The political will to build an alternative E-W corridor across the Caspian, and to spend whatever it took to deliver it without Volga-Don cable ships, was supplied by the same geopolitical event that made every incumbent Russian transit path a liability.

Try It Yourself

Every measurement ID in this piece is public. The RIPE Atlas API will return the raw traceroute results of the wave we ran on 23 April 2026 at any time: 167108382, 167108383, 167108384, 167108385. Rerun any of them — or, more pointedly, rerun the same measurements in early 2027. The difference between a 100-millisecond path through Moscow and a 30-millisecond path across the Caspian seabed will be visible to anyone with an Almaty or Baku shell account and five minutes.

This is the second piece in a short series on countries whose internet topology tells a structural story. The first piece looked at Turkmenistan, the extreme case of routing around the physical world. This one looked at what it takes — geopolitically, logistically, legally — to route with the physical world. The next piece will look at North Korea, where the question is simpler: traceroutes run toward it and do not find a path at all.