A top cruising expert has urged passengers to do one thing as soon as they enter their cabin for the first time that could prove vital in an emergency. Whilst some tourists may be fearful, cruise ships are particularly safe environments, having thoroughly-rehearsed plans to keep all passengers protected in the event of an issue occuring on board.

However, Dr. Steve Burgess, CEO and Founder of CME Vacations, suggested that tourists who feel concerned whilst travelling on board a ship should put a water bottle on the floor. He explained: "From organising medical conferences on cruise ships, I've learnt that safety often comes down to simple, proactive measures. The water bottle trick is something I teach all our physician attendees. It costs nothing, takes seconds to implement, and could provide the early warning that makes all the difference in an emergency.

"What makes this tip so valuable is that it works while you sleep. Most emergencies at sea happen overnight when passengers are least alert and most vulnerable. Having this passive monitoring system in place gives you peace of mind and potentially crucial extra minutes to respond appropriately."

By placing a clear water bottle on the floor of their cabin, tourists are able to detect three issues as soon as they begin to occur, including stability issues that the ship may have.

If the water in the bottle features ripples while the sea is calm, it could be a sign that the ship has developed mechanical issues. Serious movement within the bottle will likely wake up the passengers in the cabin at night.

Any condensation on the outside of the water bottle could also help guests to quickly identify a fire that has broken out nearby, with smoke entering the cabin from underneath the door.

Whilst Steve reassured passengers that they can trust the safety measures taken by the cruise lines, putting a water bottle on the floor can help spot issues and raise any concerns with staff members.

He added: "Ship safety systems are excellent, but they're designed to detect problems once they've reached a certain threshold. Your personal water bottle can alert you to subtle changes before the situation becomes severe enough to trigger alarms.

"While cruise ships today are incredibly safe, and serious incidents are rare, being prepared is something we emphasise in medicine—and it applies equally to travel. This simple habit has become second nature for experienced cruisers, but it's almost never mentioned in the safety briefings."