NGA Indian Ocean Nautical Chart

The Indian Ocean is one of the world's major maritime regions, linking East Africa, Madagascar, the Mascarene Islands, India, Sri Lanka, the Maldives, the Seychelles, the Andaman and Nicobar Islands, Indonesia and Australia. It also includes strategic shipping routes such as those passing through the Gulf of Aden, Arabian Sea, Bay of Bengal and approaches to the Strait of Malacca.

In such a vast maritime environment, an NGA Indian Ocean nautical chart provides a consistent cartographic representation for planning and conducting international and offshore voyages. Charts published by the National Geospatial-Intelligence Agency (NGA) cover major ocean routes, coastal areas and several strategic sectors of the Indian Ocean.

Nautic Way Maritime Bookshop offers a selection of NGA nautical charts for the Indian Ocean, suitable for planning ocean crossings, offshore navigation, yacht deliveries and international maritime routes.

What is an NGA Indian Ocean nautical chart used for?

An NGA Indian Ocean nautical chart is primarily a charting and voyage-planning tool designed for international navigation. It provides an overall view of a very large maritime area and allows sailors to plan a route before moving on to larger-scale charts for coastal approaches.

It can be used to:

• plan an Indian Ocean crossing;

• plan a voyage between Africa and Asia;

• prepare a route between Madagascar, the Mascarene Islands and India;

• navigate between southern Africa and Australia;

• plan a passage towards the Maldives or Seychelles;

• study routes around Sri Lanka and the Bay of Bengal;

• prepare a voyage towards Indonesia and Southeast Asia;

• analyse major Indian Ocean shipping routes;

• plan an offshore passage or yacht delivery.

A small-scale chart provides a global overview of the route, which is essential when several hundred or several thousand nautical miles separate the departure point from the destination.

Coverage of the main Indian Ocean routes

The Indian Ocean encompasses a remarkable variety of geographical and maritime environments. A route may cross open ocean areas before approaching particularly complex coastlines or archipelagos.

NGA charts cover areas including:

• the western Indian Ocean;

• Madagascar and its approaches;

• the Seychelles and Mascarene Islands;

• the Arabian Sea;

• the Maldives;

• the Bay of Bengal;

• Sri Lanka;

• the Andaman and Nicobar Islands;

• approaches to India;

• the East African coast;

• routes towards Indonesia and Australia.

Some charts cover very large ocean areas, while others are intended for more specific regions. The appropriate scale therefore depends directly on the type of navigation being planned.

Navigation between Africa, Madagascar and Asia

The Indian Ocean is particularly important for sailors undertaking world voyages, intercontinental passages or yacht deliveries.

A sailing yacht leaving southern Africa for Madagascar, the Seychelles, the Maldives or India may require several levels of chart coverage.

A small-scale chart can first be used to establish:

• the general route;

• distances between destinations;

• major land areas;

• principal charted dangers;

• shipping routes;

• traffic areas;

• possible diversion routes.

When approaching the coast, it should then be supplemented with larger-scale nautical charts suitable for coastal navigation and port approaches.

Madagascar and the western Indian Ocean

Madagascar occupies a strategic position in the Indian Ocean. The island lies close to major routes linking southern Africa with the Mascarene Islands and the tropical regions of the western Indian Ocean.

NGA charts covering Madagascar can be used to plan navigation around the island, particularly during yacht deliveries or extended cruising.

They provide an overall representation of:

• the Malagasy coastline;

• major islands and archipelagos;

• shipping routes;

• offshore areas;

• charted dangers;

• available hydrographic information.

For coastal navigation around Madagascar, more detailed charts are naturally required. For example, NGA 61500 Madagascar – South Coast is a 1:1,000,000-scale offshore chart covering the southern coast of Madagascar.

Arabian Sea and Bay of Bengal

The northern part of the Indian Ocean is particularly strategic. It includes the Arabian Sea, approaches to India, Sri Lanka and the Bay of Bengal.

These areas are characterised by:

• heavy commercial shipping;

• major international shipping routes;

• important port areas;

• tropical weather conditions;

• the influence of the monsoon;

• changing currents;

• very extensive navigation areas.

A nautical chart helps place a local route within its broader maritime context.

For navigation around India, it can be supplemented with charts published by the Indian National Hydrographic Office, particularly when approaching coastlines, ports or channels.

The importance of monsoons in the Indian Ocean

Navigation in the Indian Ocean cannot be separated from weather planning.

The monsoon plays a major role in passage planning, particularly between Africa, India, Sri Lanka, the Maldives and Southeast Asia.

A nautical chart does not provide all the weather information required for navigation. It does, however, provide the cartographic framework on which sailors can:

• plan their route;

• identify possible stopovers;

• calculate distances;

• plan alternative routes;

• locate strategic straits and passages;

• anticipate changes between maritime regions.

Planning an Indian Ocean crossing therefore requires a combination of nautical charts, weather information, navigational publications and current maritime information.

What information is shown on an NGA nautical chart?

Depending on the scale and geographical area, an NGA chart may show a wide range of information useful for navigation:

• soundings and depths;

• seabed characteristics;

• isolated dangers;

• reefs and shoals;

• wrecks;

• islands and islets;

• channels;

• shipping routes;

• ports and maritime infrastructure;

• lights and lighthouses;

• buoys and other aids to navigation;

• regulated areas;

• maritime traffic information.

The charts use international charting conventions, allowing navigators familiar with international nautical standards to quickly identify the main navigation information.

Which scale should you choose for navigation in the Indian Ocean?

Scale is an essential factor when selecting a nautical chart.

An NGA small-scale Indian Ocean chart provides a very broad view of the ocean and is particularly useful for planning a long-distance passage.

A larger-scale chart provides considerably more detail and becomes necessary when a vessel approaches:

• a coastline;

• an archipelago;

• a port;

• a channel;

• an anchorage;

• an area containing numerous navigational hazards.

It is therefore generally necessary to build a set of complementary charts rather than rely on a single chart covering the entire voyage.

NGA paper charts and electronic navigation

Even when a vessel uses GPS, a chartplotter or an electronic navigation system, the paper chart remains an important tool for offshore voyage planning.

It allows sailors to:

• immediately visualise a very large geographical area;

• plan the overall route;

• compare different navigation options;

• monitor the progress of a voyage;

• maintain a navigation reference independent of electronic equipment.

For an Indian Ocean crossing, a paper chart also provides useful redundancy in the event of a power problem, chartplotter failure or electronic system malfunction.

It should not, however, be regarded as sufficient for every stage of navigation: coastal and port approaches require much more detailed charts.

NGA charts, SHOM and national hydrographic charts

A common question concerns the difference between an NGA chart and a chart published by a national hydrographic service.

The NGA provides extensive international coverage particularly suited to major maritime routes and offshore navigation.

National hydrographic offices, on the other hand, generally produce official charts for their own waters, with levels of detail specifically adapted to coastal and port navigation.

In the Indian Ocean, it can therefore be useful to combine:

• an NGA chart for the offshore overview;

• national hydrographic charts for coastal approaches;

• larger-scale charts for ports and anchorages;

• relevant nautical publications and sailing directions;

• weather information and navigational notices.

This complementary approach is particularly important for long-distance voyages.

NGA nautical publications for the Indian Ocean

Charts are only one part of the documentation required for ocean navigation.

NGA also publishes Sailing Directions, providing additional information about coastlines, ports, dangers and navigation conditions.

For the Indian Ocean, Pub. 171 – Sailing Directions (Enroute), East Africa and South Indian Ocean, 15th edition 2026, covers East Africa and the south-western Indian Ocean.

For serious voyage planning, nautical charts and sailing directions should therefore be regarded as two complementary sources of navigation information.

Updating NGA nautical charts

Chart updates are essential.

Always check:

• the chart edition;

• available corrections;

• Notices to Mariners;

• the latest navigational information;

• changes to aids to navigation;

• changes affecting regulated areas or maritime infrastructure.

The NGA charting portfolio is also evolving, particularly with the gradual transition of some digital products and the reorganisation of its chart portfolio. It is therefore important to check the current status of the specific product and the latest official information.

Who are NGA Indian Ocean charts for?

An NGA Indian Ocean nautical chart may be useful to many different users:

• sailors planning an Indian Ocean crossing;

• world cruisers;

• skippers and yacht delivery crews;

• professional mariners;

• shipowners;

• commercial vessels;

• offshore fishermen;

• maritime schools and training centres;

• crews preparing an offshore passage;

• sailors planning routes between Africa, Madagascar, India, the Maldives or Asia.

They are particularly relevant whenever navigation extends beyond the immediate coastal environment and requires a charting overview at ocean scale.

Nautic Way Maritime Bookshop expertise

Nautic Way Maritime Bookshop specialises in nautical charts and navigation publications, with more than 20,000 references, including paper and digital nautical charts, navigation books, guides, sailing directions, almanacs, nautical ephemerides, training books and regulatory publications.

For navigation in the Indian Ocean, the challenge is not simply finding a chart. It is determining which areas need to be covered, which scale is appropriate and which complementary charts should be carried.

This approach is particularly important for voyages connecting several countries or continents.

Conclusion: a chart designed for long-distance Indian Ocean navigation

The NGA Indian Ocean nautical chart is particularly well suited to planning international and offshore voyages.

It provides an overall view of maritime routes linking Africa, Madagascar, the Mascarene Islands, India, Sri Lanka, the Maldives, the Seychelles and Asia.

For optimum use, it should be supplemented with larger-scale charts for coastal and port approaches, together with the navigational and weather information required for the voyage.

The NGA chart provides the ocean-scale overview; larger-scale charts then support each individual stage of navigation.

FAQ – NGA Indian Ocean Nautical Chart

Which nautical chart should I choose for an Indian Ocean crossing?
The choice depends on the planned route. An ocean-scale chart can be used to plan the overall passage, while larger-scale charts are required for coastal approaches.

Are there NGA charts covering Madagascar?
Yes. The NGA portfolio includes charts covering parts of the coast of Madagascar, including NGA 61500 for the southern coast.

Which chart should I use for navigation between Madagascar and the Seychelles?
An NGA offshore chart can be used to plan the general route. More detailed charts should then be used for approaches to the islands and ports.

Is an NGA chart suitable for sailing across the Indian Ocean?
Yes. It is particularly suitable for offshore passage planning. It should nevertheless be complemented by detailed coastal charts, weather information and the appropriate nautical publications.

Do NGA charts cover the Arabian Sea and Bay of Bengal?
The NGA portfolio includes extensive coverage of the Indian Ocean and its adjoining seas. The exact choice depends on the specific chart reference and scale required.

What is the difference between an NGA chart and an Indian hydrographic chart?
NGA provides international coverage particularly useful for major routes and offshore navigation. Charts published by the Indian National Hydrographic Office are specifically suited to Indian waters and their coastal approaches.

Do I need a paper chart for navigation in the Indian Ocean?
A paper chart is an excellent voyage-planning tool and provides valuable redundancy in the event of electronic equipment failure. It should be used alongside other navigation methods and the detailed charts required for the planned route.

Which publications should be used with an NGA Indian Ocean nautical chart?
Charts can be supplemented with Sailing Directions, Notices to Mariners, tide and current information, weather data and national hydrographic charts covering the coastal areas along the route.