Almost every Prelims paper has a few questions that are, at heart, map questions: which countries border a sea, which strait connects two water bodies, which river flows through a capital, which desert lies in which country. They are usually triggered by the news — a shipping crisis, a dam dispute, a conflict — but they test stable map knowledge.

What UPSC asks

Prelims: pair-matching and “how many of the above” questions on straits, rivers, mountains, deserts, lakes and the countries around them; north-to-south or west-to-east ordering of places.
Mains GS I and GS II: the strategic and economic significance of chokepoints and waterways; distribution of key natural resources; geography behind international disputes.

Key sub-topics

Theme	Focus
Straits and chokepoints	What each connects and separates; why it matters for trade and energy
Canals	Suez, Panama, Kiel
Rivers	Source, mouth, countries crossed, dams and disputes
Mountains	Fold and block ranges; highest peaks of continents
Deserts	Hot and cold deserts and the reasons for their location
Lakes and seas	Largest, deepest, saline lakes; seas and their neighbours

Method: keep an atlas open; for every place in the news, note its neighbours, the water bodies around it, and one physical feature.

Start with Straits, Rivers, Mountains and Deserts.