Concept:
Mangrove forests are salt-tolerant forests that grow in tidal coastal regions where seawater and freshwater mix.
Step 1: Identify the habitat.
Mangroves are commonly found in
• Coastal deltas,
• Estuaries,
• Tidal creeks,
• Marshy coastal regions.
Step 2: Analyse the options.
• Mountains -- Incorrect.
• Plateaus -- Incorrect.
• Deserts -- Incorrect.
• Coastal areas -- Correct. \checkmark
Step 3: Final conclusion.
Therefore, mangrove forests grow in
\[
\boxed{\text{Coastal areas}.}
\]