Admissibility of Nicaragua’s claim for delimitation of a continental shelf extending beyond 200 nautical miles — New claim — Original claim concerned delimitation of the exclusive economic zone and of the continental shelf — New claim still concerns delimitation of the continental shelf and arises directly out of maritime delimitation dispute — No transformation of the subject‑matter of the dispute — Claim is admissible. Consideration of Nicaragua’s claim for delimitation of an extended continental shelf — Colombia not a party to UNCLOS — Customary international law applicable — Definition of the continental shelf in Article 76, paragraph 1, of UNCLOS forms part of customary international law — No need to decide whether other provisions of Article 76 form part of customary international law — Claim for an extended continental shelf by a State party to UNCLOS must be in accordance with Article 76 — Nicaragua not relieved of its obligations under Article 76 — “Preliminary Information” submitted by Nicaragua to the Commission on the Limits of the Continental Shelf — Continental margin extending beyond 200 nautical miles not established — The Court not in a position to delimit the boundary between the extended continental shelf claimed by Nicaragua and the continental shelf of Colombia — Nicaragua’s claim cannot be upheld.