Marine Drive runs in a long flat arc along the western edge of South Mumbai from Nariman Point to Girgaon Chowpatty — about 3.6 kilometers of seawall, basalt-block promenade, and Art Deco frontage that gets its nickname from the way the streetlights string the curve at night. In the daytime, in May or June, the promenade is hot. The sea reflects, the basalt holds heat, and the shade is whatever you can find on the inland side of Marine Drive itself — which is not much, because the Deco buildings are set back behind a wide service road. The window in which the walk works is the hour before sunrise to the hour after, when the breeze off the Arabian Sea pulls the temperature down five or six degrees and the eastern Deco facades throw a faint shadow west across the prom.
The picks below assume that window. The premise is that you are walking before the city wakes — which in Mumbai means before about 6:30 — to use the only continuous outdoor shaded run in the southern part of the city. Stay Cool grades these for the actual sun angle at sunrise plus thirty minutes; in pre-monsoon May the geometry is at its tightest. A practical note: the seawall is uneven and the promenade is shared with morning joggers; walk against the run direction (north to south) and you’ll find a clean line.