Digital Infrastructure · Subsea cables

What flows through a subsea cable — and how it pays

A submarine cable laid across an ocean carries data between continents on fibre pairs. The operator sells that capacity — long-term IRUs to anchor tenants plus shorter leases & services. The cable costs the same to run (a standing fleet of repair ships) whether it's full or empty, so the economics turn on how much capacity is sold, the price per Gbps, and the cable's design capacity — lighting more fibre drops almost straight to EBITDA.

45%
£1,000
250 Tbps
LIVE
Lit capacity data on the fibre pairs IRU £ long-term anchor capacity Lease & service £ shorter-term Operating cost incl. marine maintenance
Flows — annualised from current assumptionsper year
Revenue p.a.
£0
£0 / hr
EBITDA p.a.
£0
0% margin
Revenue / Gbps·yr
£0
blended price
Capacity sold
0
45% of design
Stocks — what the flows accumulate intolive
Capacity lit now
0
live, of 250 Tbps design
EBITDA banked · session
£0
accumulating in real time
Implied enterprise value
£0
at 14× EBITDA
Where revenue comes from Total £0 p.a.
IRU / anchor
Leases & services
Why investors like it: anchor tenants (carriers and hyperscalers) pre-buy fibre pairs or spectrum on 15–25 year IRUs that often underwrite the build before it is laid — a contracted annuity on a scarce, hard-to-replicate route. Shorter leases and O&M services add an upside layer. But the marine-maintenance cost base is fixed, so filling the cable is what creates the value; an empty cable still pays for its repair ships.
Revenue streams£0 p.a.
Operating costs£0 p.a.
Investment case — should you buy it?DCF returns

Year-1 financials flow live from the simulation above: revenue £0 and EBITDA £0 p.a. Set your deal terms below — the unlevered IRR (asset return) and levered IRR (return to equity, after debt) recompute instantly.

Operating

%
%
%
%
%
%

Valuation & hold

×
×
y

Financing

×
%
%
Unlevered IRR
—
asset / project return
Levered IRR
—
return to equity
Equity multiple
—
MOIC over hold
Equity gain
—
exit equity − invested
Equity cash-flow profile£m · ■ invested   ■ returned
Projection — £m per year

Illustrative model. Represents a long-haul submarine cable system with a design capacity (Tbps) of which a share is sold/lit. Revenue = capacity sold × price per Gbps, split into long-term IRU/anchor contracts and shorter leases & services. Operating costs are dominated by fixed marine maintenance (standing repair-ship agreements), landing stations, network operations, restoration and insurance — so margins swing hard with how full the cable is (it can be loss-making when lightly sold). EBITDA = revenue − operating costs; excludes the upfront build/lay capex. The investment case is a simplified DCF. For illustration only — not investment advice, and not any specific asset.