The Setup
Over the 30 days ending October 9, one H3 cell in Table Bay off Cape Town, South Africa (88ad36153bfffff) logged 74,515 AIS positions — the seventh-highest position count of any cell network-wide in that window, trailing only a cluster of Rotterdam/Antwerp-area cells already covered in this series. Broken out by vessel_type, 62,409 of those positions — 83.8% — came from vessels classified other. Every standard classification combined — general_cargo, bulk_carrier, tanker, fishing — accounts for the remaining 16.2%.
The Chain
The other bucket isn't a small or rare label. Network-wide over the same 30 days, other is already the single largest vessel_type by position volume: 10,748,594 of 24,491,220 positions logged across all cells and types — 43.9%. At the fleet level, other is the second-largest classification Axiom tracks: 19,658 of 67,600 vessels (29.1%) carry no finer type than this fallback. Cape Town's lead cell runs at nearly double that already-elevated network share.
The volume isn't coming from a large number of vessels. other-type activity in this cell averages 10.3 unique vessels a day, peaking at 13 — fewer than the general_cargo and bulk_carrier vessels sharing the same water, which together account for just 16% of positions despite comparable vessel counts. A handful of unclassified vessels are each transmitting on the order of 200 positions a day, consistent with stationary AIS reporting from vessels that are anchored or loitering rather than underway.
The cell's daily total has also been sliding across the window: 3,317 positions on September 9, down to a range of 1,477–2,270 by early October — a decline of roughly 40% inside the same 30 days, concentrated in the same small set of other-classified vessels.
The Implication
In a density view that weights cells by raw position count rather than unique-vessel count, this cell reads as one of the busiest, least-identifiable spots in the network: nearly all of its signal is attributed to vessels the fleet-type model can't otherwise categorize, and that concentration is sharper here than the system's baseline rate for the same fallback bucket.
What to Watch
Whether the declining daily count continues through October or stabilizes, and whether any of the other-classified vessels in this cell resolve to a named type as vessel-registry enrichment catches up — which would pull the cell's classified share toward the general_cargo/bulk_carrier/tanker split seen elsewhere.
Limitations
Position density conflates reporting frequency with vessel count — a few stationary vessels broadcasting every few minutes can outweigh many vessels that are underway and transmitting less often, and this piece can't separate the two further than unique_vessels already does. No claim is made here about why these particular vessels fall into other or why the cell's volume is declining (vessel-type enrichment lag, fleet turnover, anchorage practice, and routing all sit outside what density counts alone can show). The 30-day window also doesn't establish whether this cell's other concentration is a persistent feature of this anchorage or specific to this period.
Data as of 2026-10-09. Source: vessel_density_h3_daily_inc, h3_index 88ad36153bfffff (Table Bay, Cape Town), 30-day trailing window; network and fleet baselines from the same table and vessels. Axiom Overwatch.