How Long Can You Survive In Open Water?

How long can you survive in the open water? Well, how long a person can survive in the open water is determined by several things. For one, people stranded on a boat or life raft can survive several days longer than the poor souls stuck in the water with just a life jacket.

The supplies you have with you also determine how long you can hold out before being rescued. The human body can survive for an impressive two to three months without food, but it will not last longer than a week without drinking water.

Being stranded at sea is just about everyone’s worst nightmare. Even the thought of being alone on the water with no land in sight sends shivers down my spine. Nevertheless, you may be surprised how long some people have survived while being adrift at sea.

Though it is a grim and terrifying experience, some people have survived hundreds of days in open water, while others have died after just a few hours. I am going to discuss the following in this article:

⏲️ How Long Can You Survive In The Open Water?

Right from the start, I can tell you that if you are stranded at sea without food or water, the chances of making it out of there are extremely low.

The sad reality is that a stranded person will be lucky to stay alive for more than a week without water. 

Trying to stay alive without water on land is hard enough, but the challenge can be even greater when you are lost at sea. You are constantly surrounded by water, yet it is not water you should drink. The temptation must be unbearable. 

Sailors who find themselves stranded on something that floats, like a boat or raft, will likely be able to survive for a longer time than lost scuba divers or sailors who have gone overboard. Then again, your survival ability dramatically depends on how much food and water you have. 

Some People Have Survived Hundreds Of Days In The Open Water

Though most stories of people stranded on the ocean have a sad ending, there are a few that you might call extraordinary.

Even without having food or water on board his vessel, the Mexican fisherman Salvador Alvarenga managed to survive at sea for an incredible four hundred and thirty-eight days. You can check out this incredible story below:

It is amazing what human beings can and are willing to do to stay alive. Alvarenga managed not to starve to death by catching fish with his bare hands.

He put his arm in the water with his hand open, taking the risk that a curious shark might come to take a bite, and waited for fish to swim through, at which point he would close his hand and grab the fish.

And before he could harness some rainwater for the first time on day fourteen, he had no choice but to drink his urine and turtle blood, which barely kept him hydrated.

Amazingly, even after two weeks, the Mexican fisherman did not give in to the temptation of drinking the seawater. 

🌊 Factors That Determine How Long You Can Survive In Open Water

Your ability to survive in open water is dependent on many factors. Rescue teams must consider many things when estimating how long a stranded person has before being gone forever.

The main things to consider are the following:

  • Is the person stranded on a boat?
  • Is the person stranded on a raft?
  • Is the person stranded in the water?
  • Is the water warm or cold?
  • Is the person stranded in shark-infested waters?

People On A Boat Can Survive The Longest In Open Water

If I could choose how I want to be stranded at sea, like most people, I would like to be on a boat.

Sailors whose boat engines and radios stop working can stay alive if they can fish and harness rainwater. This is the most ‘comfortable’ way to be stranded at sea.

People who hold undesired records for being stranded at sea for the longest time, like Salvador Alvarenga and Oguri Jukichi, were adrift on boats. Had they been on a raft, or other floatation devices, it is unlikely that these survivors would have made it home.

Having some cover on your vessel is crucial to your survival in these scenarios. It will protect you from the harsh and unforgiving sun and keep you somewhat warm at night. It will also come in handy when harvesting rainwater. 

There is always the possibility that a storm will come and make your life even harder, yet there is not much you can do besides praying to Poseidon to have mercy and not capsize your boat.  

A Good Life Raft Can Keep You Alive For Long In Open Water

Being stranded on a raft is much less desirable than being stranded on a boat. SOLAS life rafts are very well-designed and equipped nowadays, but they still have a greater chance of sinking than a boat. 

Either way, it is good to know that today’s life rafts are well-designed and equipped to maximize your chances of survival. If you are ‘lucky’ enough, you can end up in a raft with the tools needed to survive for a while.

A well-equipped raft should, at the very least, have the following:

  • A fishing kit. Though some non-perishable foods should be on board, this food could run out depending on how long you are adrift. Having a fishing kit will save your life in this scenario.
  • Flares. The main goal when you are lost at sea is to be found. Flares enable you to be seen when a boat passes you by.
  • Buckets. Water will inevitably get into your raft, especially if you are lost in rough waters. Having a bucket to empty the water from the raft is another lifesaver.
  • Cover. In ordinary life, many people try to catch good sun exposure to get a nice tan. However, when you are adrift at sea, you want to avoid a heat stroke, so having some cover on your raft is important to your survival. 
  • Water collection bags. If you are stranded on a raft or boat, death from dehydration is one, if not the most probable scenario. If it rains, every drop counts, so a raft should be equipped with pouches to collect as much rainwater as possible.
  • Paddles. You might see precious land in the distance as you endlessly float on the ocean. Crucially, having paddles to move and steer the raft can make the difference between reaching the land or just passing by it.
  • Signaling Mirrors. Though flares are the go-to device to signal ships or planes when you are stranded, it is sadly not a guarantee that you will be seen before you run out. Mirrors can be used as a signaling device by reflecting sunlight in the direction of the ship or plane whose attention you are desperately trying to get. 
  • Floors with insulation. Avoiding exposure to extreme heat and cold is another important aspect of survival, whether on or on land. Insulating floors in your raft can help better regulate the temperature inside the raft, helping you avoid contracting hypo-or hyperthermia.

You Cannot Survive Very Long When Stranded In The Water

Ending up stranded in the water with no floatation device is just about the worst-case scenario I can think of; you truly are at the ocean’s mercy in this scenario.

The little good news is that your wetsuit will help keep you afloat if you are a scuba-or-free diver. Having a life jacket also goes a long way in keeping you floating and alive, avoiding the exhaustion of swimming to keep your head above water.

The bad news is that you quickly have to deal with much bigger problems, especially if rescuers are not coming anytime soon.

Without food or drinking water and no way of catching fish or rainwater, it is unlikely that a person can survive in the water for more than a few days or hours. You will likely die from dehydration or hypothermia.

If you ever have the misfortune of finding yourself adrift at sea with no boat, raft, or life jacket, know there is still hope that you will survive.

Everyone can take inspiration from Kay Longstaff’s story. After falling off the back of a cruise ship in Croatia while on holiday, Kay Longstaff had to survive for ten hours before being rescued.

The British women did not have a life jacket on but managed to stay afloat, thanks to the calm and flat conditions of the Mediterranean Sea. 

Fortunately for Longstaff, the Mediterranean Sea has warm water. She fell into 80°F water, which is around the temperature of a swimming pool.

At that temperature, it takes longer for the human body to develop life-threatening conditions like hypothermia.  

Cold Water Decreases Your Chances Of Survival In Open Water

If you find yourself stranded in open water, you better hope the temperature is above 80°F like it was for Kay Longstaff. At this temperature, you will be able to survive for about a day. 

The colder the water temperature, the greater the shock to your body. After a few hours, your core body temperature falls to hypothermic levels where your body can no longer function. 

Hypothermia settles in when the human body loses more heat than it generates, resulting in a critical drop in core body temperature. Unfortunately, getting wet and constantly being exposed to the water rapidly accelerates hypothermia symptoms. 

You could reduce the likelihood of contracting hypothermia if you could dry yourself, but this is not possible when you are stuck in the water.

You will be lucky to survive longer than six hours in 60°F water. To illustrate just how bad being stuck in cold water is, many of the Titanic survivors who got stuck in the 28°F water died within an hour.

Some Open Water Areas Are Full Of Hungry Sharks 

Sharks are not the monsters that Hollywood has made them out to be. But if you find yourself floating in the open ocean, whether on a boat or in the water, it is only natural for creatures to be curious.

Unless you swim in the middle of a shiver of sharks, you will have to worry about starving and dehydration, more so than a shark biting your leg while adrift at sea. 

However, the possibility of being attacked by a shark while stranded is still real. The story of the USS Indianapolis survivors is a harsh reminder of that.

The sailors suffered from dehydration and starvation while being picked apart by sharks.

⛵ Sailors Must Have The Right Equipment In Open Water 

How you prepare for a potential worst-case scenario at sea can result in things either going well or badly if that scenario takes place. 

Though there are many types of boats that sailors can embark on, whether a yacht, sailboat, cruise ship, oil tanker, etc., sailors should generally have the following safety and sea survival equipment on board their boat.

  • First aid kit to treat injuries
  • Life Jackets/life vests to stay afloat in case of emergency
  • VHF radio to call for rescue
  • Satellite phone to call for rescue
  • Knife to cut entangled ropes
  • Tool kit for repairs
  • Signaling devices to call for help
  • Well-equipped lifeboat/raft
  • Paddles and oars if there is an issue with the engine
  • Buckets or other bailing devices to dewater the vessel
  • Powerful flashlights

A Grab Bag Is Essential For Survival In Open Water

Hopefully, it never comes to this, but if a sailor and their crew are forced to abandon ship, they must take a grab bag, also known as a ditch or panic bag, with them.

A well-equipped grab bag will increase your chances of survival following the abandonment of the ship, and the equipment stored inside can dramatically increase your chances of being rescued.

A good grab bag must be waterproof and made from durable materials. Its location on the boat should also be known to all the crew members. Here is what the ideal bag should contain:

  • Drinking water. Drinking water is hard to come by on the open ocean, so it is necessary to have as much water as possible in the emergency bag.
  • Water maker. A water maker can convert seawater to drinking water.
  • Non-perishable food. Food is also hard to come by in the open water. A fair amount of rations should be packed, especially when trips are far from the coast.
  • First aid kit. Medications and bandages to treat injuries.
  • VHF radio. Sailors adrift can call for rescue using a VHF radio. Some spare batteries should also be packed in the bag. Some VHF radios have an integrated GPS that can give rescuers the survivor’s location.
  • Signaling devices. Signaling devices like flares and mirrors can help draw attention from potential rescuers.
  • Fishing kits. A fishing rod will come in handy once survivors have run out of food.
  • Flashlights. It gets pretty dark at night on the water, as there is no light population.

What’s The Longest Someone Has Survived Lost At Sea? 

As of 2022, Japanese sailors Oguri Jukichi and Otokichi hold the record for surviving the longest time adrift at sea. The two sailors were stranded for four hundred and eighty-four (484) days from 1813 to 1814.

Jukichi’s ship mast was destroyed in a storm on a voyage in the Pacific. Ultimately, the ship drifted over five thousand miles to reach California. Jukichi and Otokichi were the only survivors of the crew.

🌊 How Do People Survive Being Left In The Open Ocean? 

There is no shortage of incredible survival stories in the open ocean. Many of the survivors have, one way or another, managed to stay fed and hydrated, which are the two most critical things. 

Some people are more fortunate than others and end up on a lifeboat or raft that is well-equipped to extend their survival. Some survivors have depended on drinking rainwater, urine, and even animal blood to stay hydrated and alive.

🛟 What Is The First Rule Of Ocean Survival?

Water is life. Without drinking water, you will be lucky to survive longer than a week. Finding and securing drinking water is the most important thing you can do in the first moments of being stranded.

In addition, not drinking seawater while you are adrift at sea is just about as important. The temptation to drink seawater is great amongst survivors, especially if they are dehydrated. But drinking seawater only increases dehydration.

🗣️ Final Words

Surviving in open water is a harsh challenge. Even if you are on a boat or raft, a lack of food and water will decrease your chances of survival dramatically. A person can only last up to a week without water before dying of dehydration. 

You will likely not survive for more than a day or two if you are adrift in the water, especially if the water is cold or hungry sharks are around.

I’m the founder and chief editor here at Sailing Savvy. I spent a decade working as a professional mariner and currently, I mix those experiences with digital publishing. Welcome, and I hope that we can be the hub you need for safe passage.