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World-building questions about an island chain in the southern Indian Ocean

Miles Lacey

Looking at an older Britannica Atlas map a group of islands that follows the Mascarene Plateau until 10°S then along the Mid-Indian Ridge in a northeastern direction until about the 7°S mark could be created Another string of islands could be created along the Chagos Laccadive Plateau in a northeast to north direction until about 4°S. An island on the Mid Indian Ridge would act a bit like Hawaii has done for the 150 odd years. Between the Ninety East Ridge and about Java are a string of raised areas of sea floor which include our world Christmas and Cocos (Keeling) Islands which could be made islands.

Keeping the islands small (generally between about 300 km² and 3000km² should work.

That would allow a generally tropical, west to east string of islands that stays above the Tropic of Capricorn and below the Equator is good. With one or two exceptions the islands would stick to the tectonic plates. The island on the Mid-Indian Range would be the size of Puerto Rico (about 9104 km²).

I picture an Austronesian based race island hopping from the east and another race island hopping from the west. Along the way they encounter a South Asian race that has come from the North (due primarily to storms and monsoons). With the meeting of the three races a multi-cultural society emerges.

Could this work?


At the end of last year I dumped my work in progress. I liked the basic storyline but the worldbuilding aspects just didn't do it for me.

What I have in mind is an island chain made up of islands with the same topography as Sakhalin, Japan and Taiwan stretched out between the southeast coast of Madagascar and western Australia.

The key things I would be interested in knowing would be:

1. What physical characteristics would the people of such islands have?
2. How densely populated would such an island nation be? I strongly suspect that the population of these islands would be a fraction of those who live on the coasts of eastern Africa and South Asia.
3. What crops, livestock and foods could be produced here?
4. What would the climate be like? I envisage a very cold and hostile climate on the parts facing Antarctica and a warmer (temperate?) climate on the parts facing away from Antarctica.
5. Would there still be monsoons in the Indian Ocean? If so, would they be more powerful, less powerful or about the same?

Any feedback would be welcome.
I appreciate the influences of the ocean currents and the wind, but I'm not so sure about the south-facing (facing Antarctica) coasts being 'very cold and hostile,' if they're strung out, as you say, between Madagascar and Western Australia. Here, they're in a warm/hot latitude and much further North than New Zealand's South Island (mentioned elsewhere in the replies).


Myth Weaver
The Galapagos may also be on use to look at. They are an island group deep in the middle of an ocean. They may not affect the currents around all that greatly, but the currents certainly have an effect on the life on and around the isles.

Miles Lacey

Who knew that by asking what seemed to be a relatively straightforward question would lead to learning a lot about ocean currents, trade winds, ocean gyres and the monsoon - not to mention the Indian Ocean itself? For me, it looks as if it's back to the drawing board as far as the worldbuilding is concerned.

The feedback has been excellent and has certainly helped to add a richness and flavour to my world, especially as it introduced me to the Sunda culture and people. Their housing resolved a big worldbuilding question for me and many of their cultural and social customs blend in very well with the cultures I'm working on for my work in progress.