Phone, battery and signal

Several hundred thousand people in a few square kilometres, all with phones, all uploading video. Cell capacity is finite and Pujo comfortably exceeds it around the major pujas on the peak nights.

You will typically see full signal bars and no usable data. Calls sometimes get through when data does not. UPI payments fail, which is why cash matters.

A ten-hour evening of maps, camera and torch will flatten any phone. Carry a power bank and a short cable, and charge before you leave rather than topping up during.

Turn the screen brightness down, close the map when you are not using it, and put the phone in low-power mode early rather than at eight per cent. If you are shooting a lot of video, that alone will halve your battery life.

Decide the route before you go out. This site keeps your route on your device, so the list survives a dead network — but a live map may not, so know the neighbourhood you are walking into.

Screenshot what matters. Agree meeting points and times in advance rather than assuming you can call. Keep a paper note with a phone number on it, and enough cash to get home without an app.

Charge to a hundred per cent, download or screenshot anything you will need, add your pujas to your route on this site, and check the last Metro time for the night. Four things, five minutes, and they cover almost every way an evening goes wrong.

Tell somebody roughly where you are going. Not as a precaution against Kolkata, which is a safe city during Pujo, but as a precaution against a dead phone in a crowd of half a million people.

Uploading video from inside a pandal area on Ashtami night is the single most reliable way to flatten a battery and fail anyway. The upload will be quicker, and your evening better, from wherever you are sleeping.

The same applies to live location sharing, which drains a phone quickly and is often inaccurate in a dense crowd between tall structures. Agree a time and a place instead; it works and it costs nothing.