Driving and walking are among the safest ways to travel during a pandemic. Here's how other modes of transportation rank.

Experts have warned against any and all travel by cruise ship, as diseases can spread quickly onboard.

The CDC just extended its no-sail order for cruise ships, as this form of travel is seen as one of the most risky during a pandemic.

Experts have explained that large passenger ships can quickly become a breeding ground for illnesses like the coronavirus. Since hundreds of passengers are within close quarters of each other for extended periods of time, diseases can spread much more quickly on a cruise ship than other modes of transportation.

"What puts people more at risk while traveling is that they come in contact with lots of other people, and also there's prolonged exposure to other people and shared surfaces in a confined space," Dr. Stephen Luby, a professor of medicine specializing in infectious diseases at Stanford University, told Business Insider.

In a media release, CDC Director Robert Redfield said, "We are working with the cruise line industry to address the health and safety of crew at sea as well as communities surrounding US cruise ship points of entry.

"The measures we are taking today to stop the spread of COVID-19 are necessary to protect Americans, and we will continue to provide critical public health guidance to the industry to limit the impacts of COVID-19 on its workforce throughout the remainder of this pandemic."

Using public transportation like the subway, a train, or bus can make it difficult to social distance or avoid touching shared surfaces.

Due to subway line closures and fewer people on the subway, it may be easier to maintain distance between yourself and other passengers.

However, crowded subway cars, trains, and buses can quickly become a hotbed of contaminants due to high foot traffic and riders touching, sneezing, or coughing on shared surfaces.

In order to attempt to curb this, the MTA in New York City has modified its schedules for the Long Island Rail Road and the Metro-North Railroad, and strategically planned its subway line service during "peak" travel times.

"I understand people are trying to get somewhere, but no one should be getting on a crowded train," Mayor Bill de Blasio told local station NY1. "Spread out throughout the train, [or] wait for the next train."

If you do have to travel using public transportation, be sure to wear some sort of face covering, use the least-crowded bus or subway car as possible, avoid touching shared surfaces, sanitize your area if possible, and don't bring your hands close to your face. Travelers should also use an alcohol-based hand sanitizer or wash their hands after exiting the bus or train.

The CDC also recommends that instead of touching shared surfaces with bare hands, travelers should use a disposable tissue or even a sleeve to cover their hands or finger if they must touch something while traveling.

Ride-sharing services can be safer than public transportation but there are still risks.

Using ride-sharing services like Uber or Lyft can be risky, as it's near impossible to know who has been in the same car or if your driver may have been exposed.

However, according to a report by the New York Post, using Uber or Lyft is still safer than using public transportation.

"[The driver] is facing away from you. The likelihood of him coughing or sneezing on you is low. Plus, if he was very sick, he probably would not be working," microbiologist Jason Tetro, author of "The Germ Code," told the New York Post. "If the previous passenger was coughing and spurting and putting his germs on the seat-belt and door, there's not much you can do. You should be using hand sanitizer the second you get out of the Uber."

If you do choose to use Lyft or Uber, a single-occupancy ride is the safest way to travel, as it's near impossible to keep 6 feet from other riders in a shared vehicle. On March 17, 2020, Uber and Lyft both suspended their carpool options in the US, Canada, London, and Paris.

Traveling via airplane has its risks, but there are ways to make this method of travel safer.

According to the CDC, because of how air circulates and is filtered on airplanes, most viruses and other germs do not spread easily.

However, it's still vital for passengers to practice extreme caution and take all measures available to protect their health.

The CDC is recommending that all passengers traveling by airplane give their up-to-date contact information to the airline prior to boarding. By doing so, this ensures that if a passenger on your flight tests positive for the coronavirus, you will be notified.

The CDC also recommends that before passengers sit down or touch shared surfaces on any form of public transportation, including airplanes, they should thoroughly wipe down the area with disinfecting wipes or disinfecting spray.

If your plane happens to have empty seats, asking a flight attendant if it's alright to move to a sear farther away from others may be a way to increase social distancing and protect yourself from those who have potentially been exposed or contracted the virus.

Alaska Airlines and American Airlines have both updated their policies and released information about how to social distance while flying.

Biking is relatively low risk.

Biking, as long as it's done alone or with those you're quarantined with, is an excellent way to get some fresh air, exercise, and practice social distancing. Plus, compared to other methods of transportation, biking is relatively low risk, as long as riders are diligent about sanitizing their hands and bike handles each time they touch a surface that may have been contaminated.

Using a personal bike is less risky than using a shared Citi Bike (in New York or New Jersey) or other bike rental service. If you do choose to use a rental bike, be sure to bring along sanitizing wipes to properly disinfect the bike before and after use.

Starting April 13, employees at Citi Bike valet stations will begin to disinfect all bikes returned to their stations. However, it's also important to clean the bikes yourself to ensure they've been thoroughly sanitized after the bike's last use.

"To help with prevention, all high contact surfaces on bikes will be disinfected each time they arrive in our depot. The same is being done for our vans, used to transport vehicles, at the start of each shift. In addition, our associates are wearing gloves when handling bikes," Citi Bike wrote on Twitter.

Walking alone is also a safer option, so long as you keep 6 feet of distance between anyone else and practice proper precautions.

Many people practicing social distancing are relying on walks to maintain a healthy lifestyle and get outside. Walking is also one of the safest ways to travel during a pandemic, as long as travelers continue to practice precautions.

Keeping 6 feet of distance between other people out walking, wearing a face covering, and avoiding touching any shared surfaces like benches or traffic buttons are all ways to keep yourself safe while walking.

Traveling alone by car is one of the safest ways to travel as long as you practice proper sanitation frequently.

At this time, travelers should choose modes of transportation that provide adequate social distancing and that aren't shared by other people. A private vehicle is one of the most isolated ways to travel.

"This would be a time where you might drive your car instead of taking mass transport," Dr. Luby told Business Insider.

Each time you get into your car, sanitize your hands and the interior of the car to prevent accidental contamination.

If other people have access to your vehicle, it's even more important to wipe down areas you will touch with a disinfecting wipe to ensure they're clean from any contaminants.

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