Polar Code

The International Code for Ships Operating in Polar Waters (Polar Code) is a mandatory IMO instrument covering safety (adopted under SOLAS Chapter XIV) and environmental protection (adopted under MARPOL Annexes I, II, IV and V). It entered into force on 1 January 2017 and applies to new ships from that date; existing ships were required to comply by the first intermediate or renewal survey after 1 January 2018.

The Code recognises that ships operating in Arctic and Antarctic waters face unique risks: remoteness from search and rescue facilities, extreme cold affecting machinery and personnel, ice loads on the hull and propulsion system, limited hydrographic surveys, and severe environmental sensitivity. Requirements are goal-based — ships must demonstrate through risk assessment that the design meets safety and environmental goals.

Geographic scope

Arctic waters — broadly north of 60°N, but with specific geographic boundaries defined in the Polar Code (including the coasts of Alaska, Canada, Greenland, Iceland, Norway, and Russia). Some areas below 60°N are included; the Baltic Sea is excluded.
Antarctic area — south of latitude 60°S. The environmental provisions of MARPOL that apply in the Antarctic area impose the strictest discharge restrictions anywhere under MARPOL.

Ship categories

Category A
Medium first-year ice, which may include old-ice inclusions (≥ 0.70 m thick)
Highest capability for a conventionally designed polar ship. Includes strengthened icebreakers operating in polar waters year-round. Must comply with full structural, machinery, and safety requirements of the Polar Code.
Category B
Thin first-year ice, which may include old-ice inclusions (0.30–0.70 m thick)
Intermediate capability. Typical of modern Arctic supply vessels and research ships. Must comply with enhanced requirements compared to Category C but less demanding than Category A.
Category C
Open water or ice conditions less than those described for Category B
Minimum polar capability. A Category C vessel operates in polar waters only when ice concentrations and thicknesses are within design limits. Many cruise ships and cargo vessels are certificated Category C.

IACS Polar Classes (PC1–PC7)

The Polar Code ship categories correspond to the Polar Class (PC) system developed by the International Association of Classification Societies (IACS). PC ratings describe structural and machinery requirements for the given ice regime.

PC1
Year-round operation in all polar waters including the most severe multi-year ice. Applies to powerful icebreakers.
PC2
Year-round operation in moderate multi-year ice conditions.
PC3
Year-round operation in second-year ice, which may include multi-year ice inclusions.
PC4
Year-round operation in thick first-year ice, which may include old-ice inclusions.
PC5
Year-round operation in medium first-year ice, which may include old-ice inclusions.
PC6
Summer/autumn operation in medium first-year ice, which may include old-ice inclusions.
PC7
Summer/autumn operation in thin first-year ice, which may include old-ice inclusions.

Correspondence: Category A ships generally hold PC1–PC5; Category B ships PC6–PC7; Category C ships may have no ice class notation or a standard Baltic class (e.g., IA, IB, IC).

Polar Water Operational Manual (PWOM)

The PWOM is a mandatory document required to be carried on every ship to which the Polar Code applies. It translates the ship's design capabilities and limitations into operational guidance for the Master. Key contents:

Operational capability and limitations — including maximum design ice thickness, minimum operating temperature, and limitations on speed in ice.
Safety arrangements — cold weather survival equipment, life-saving appliances (LSA) rated for polar temperatures, communication equipment, and procedures for man-overboard in ice.
Emergency procedures — including beset-in-ice procedures, emergency towing, and contingency plans for loss of propulsion.
Environmental protection procedures — fuel oil transfer, ballast water management, and waste management in polar areas.
Voyage planning guidance — ice routing, use of icebreaker escort, POLARIS assessment, and notification of flag and coastal states.

POLARIS — risk assessment system

POLARIS (Polar Operational Limit Assessment Risk Indexing System) is the IMO-recommended methodology for assessing whether a ship can safely operate in prevailing ice conditions. It uses the Risk Index Outcome (RIO), derived by combining:

The Ice Multiplier (IM) — assigned to each ice type (multi-year, second-year, first-year thick, etc.) for the ship's polar class.
The Ice Concentration — reported in tenths of coverage (e.g., 7/10 medium first-year ice).

The resulting RIO is assessed against four operational risk levels:

Normal OperationsRIO ≥ 0
Prevailing ice conditions are within the vessel's operational capability. Normal operations may proceed.
Elevated Operational RiskRIO between 0 and threshold
Operations can continue but with enhanced monitoring and precautions. Master should document risk acceptance.
Operations Subject to Special ConsiderationNegative RIO approaching limit
Ice conditions are approaching or at the limit of the vessel's capability. Expert assessment required; consider ice management support.
Operations Should Not ProceedRIO below minimum threshold
Prevailing ice conditions exceed the vessel's ice class capability. Operations must not proceed without icebreaker escort or exceptional authorisation.

Pollution prevention

Antarctic area (south of 60°S) — Absolute prohibition on any oil or oily water discharge. No garbage discharge except food waste comminuted to less than 25 mm, disposed of at least 12 nm from land or ice shelves. No sewage discharge within 3 nm (comminuted/disinfected) or 12 nm (untreated). Carriage of heavy fuel oil (HFO) as cargo or fuel is prohibited in Antarctic waters under MARPOL Annex I regulation 43A (applicable from August 2011, with exemptions phased out).
Arctic waters — Stricter than general MARPOL standards. The IMO has adopted a ban on the use and carriage of heavy fuel oil (HFO) in Arctic waters, effective from July 2024 (with flag-state waiver option to 2029 for vessels with double-hull protection). Noxious liquid substance (NLS) discharges are prohibited. Black carbon emissions from HFO combustion are a key concern addressed under ongoing IMO deliberations.

Crew training — STCW V/4

Basic training (STCW V/4-1) — Mandatory for all officers serving on ships operating in polar waters. Covers polar geography, ice and weather, cold-weather survival, search and rescue in polar conditions, and the PWOM. Typically delivered as a 2–3 day shore-based course.
Advanced training (STCW V/4-2) — Mandatory for Masters and Chief Officers in charge of a navigational watch. Additional competencies: ice navigation, POLARIS assessment, voyage planning, use of icebreakers, ice routing, environmental awareness. Typically 4–5 days including bridge simulation.

Survey and certification

A Polar Ship Certificate is issued by the flag state Administration following survey confirming compliance with the structural, machinery, and safety requirements of the Polar Code. The certificate specifies the ship category (A, B, or C) and any operational limitations (e.g., minimum operating temperature, maximum design ice thickness). Port state control officers in Arctic and Antarctic states may inspect for the certificate and the PWOM.

Common polar routes

Northern Sea Route (NSR)Russian Arctic
Approximately 5,600 nm from the Kara Gate to the Bering Strait. Transits require a permit from FSUE Atomflot (Russia) and icebreaker escort may be compulsory. Shortest Europe–Asia routing in summer months.
Northwest Passage (NWP)Canadian Arctic Archipelago
Approximately 7,900 nm from Baffin Bay to Bering Strait via multiple routes. Governed by Transport Canada; sovereignty disputed as an international strait vs. internal waters. Navigable for limited weeks in late summer.
Antarctic tourism and researchSouth of 60°S
Tourism vessels must hold a Polar Ship Certificate. Landing in Antarctica is regulated by the Antarctic Treaty System; vessels must comply with IAATO guidelines and zero-discharge MARPOL requirements throughout.
Greenland fjords and SvalbardNorth Atlantic / High Arctic
Popular cruise and expedition routes. Svalbard is governed by Norway under the Svalbard Treaty. Ice conditions vary; most operations are Category B or C.