{"id":99,"date":"2026-04-13T15:43:27","date_gmt":"2026-04-13T15:43:27","guid":{"rendered":"https:\/\/redzine.co.uk\/index.php\/2026\/04\/13\/what-is-the-chance-of-a-message-in-a-bottle-being-found\/"},"modified":"2026-04-13T15:43:27","modified_gmt":"2026-04-13T15:43:27","slug":"what-is-the-chance-of-a-message-in-a-bottle-being-found","status":"publish","type":"post","link":"https:\/\/redzine.co.uk\/index.php\/2026\/04\/13\/what-is-the-chance-of-a-message-in-a-bottle-being-found\/","title":{"rendered":"What is the chance of a message in a bottle being found?"},"content":{"rendered":"
<\/span> Jenny Sturm\/Shutterstock<\/a><\/span><\/figcaption><\/figure>\n

Recently, a cheerful 100-year-old message in a bottle was found<\/a> on the south-west coast of Australia. In it, a world war one soldier proclaimed to be \u201cas happy as Larry\u201d.<\/p>\n

If you\u2019re a betting person, you probably wouldn\u2019t expect great odds of this happening. A bottle cast into the ocean could end up absolutely anywhere.<\/p>\n

If it floats to a remote location, there is little chance of somebody stumbling upon it. And if it lands somewhere more favourable where people could potentially find it, there are other issues. The message itself will deteriorate over time as light degrades it. If the bottle fills with water, it will sink and almost certainly never be found.<\/p>\n

So, what are the chances of a message in a bottle being found and it being over 100? And what are your chances of finding this bottle?<\/p>\n

Despite these many possibilities during a bottle\u2019s lifetime, the probability we are after is a straightforward calculation. Just count up the number of bottles with messages that have been found and are over 100 years old, and divide by the number of messages that have been sent this way (assuming we know how many are sent):<\/p>\n

Our diagram below shows a hypothetical situation where 20 bottles are sent in total, of which six are found (indicated in gold) and one of these is over 100 years old (indicated by the \u201c100\u201d stamp). So, one in 20 bottles are found and over 100 years old. (Note: This is only a hypothetical calculation, not the real data.)<\/p>\n

Instead of calculating the probability directly, another way to do it is by breaking the problem into two parts: (A) a bottle with a message is found, and (B) the found bottle is over 100. These two probabilities can be calculated separately and multiplied together to get what we want:<\/p>\n

This is known as the \u201cmultiplication rule\u201d of probability, and we confirm from our hypothetical numbers that (6\/20)\u00d7(1\/6) = 1\/20, as before.<\/p>\n

Both approaches to calculating this probability are simple. However, the direct calculation requires knowing the total number of bottles sent out, which is very difficult to know in the real world.<\/p>\n

The multiplication rule has the advantage that it breaks the calculation into two parts. We can tackle each separately, then bring the two results together to get the probability we want. This is useful in the real-world situation where we can draw information from different sources.<\/p>\n

First, we\u2019ll deal with the probability that a bottle with a message is found, irrespective of its age.<\/p>\n

Experts from the Federal Maritime and Hydrographic Agency of Germany suggest a one in ten chance<\/a> that a message in a bottle will be found. This aligns broadly with various historical \u201cdrift bottle\u201d experiments, where oceanographers released large numbers of bottles to understand ocean currents.<\/p>\n

For example, studies from the 1960s and \u201970s in the North Atlantic Ocean led to recovery rates of 14% from the Gulf of Mexico<\/a>, 8% from the Caribbean Sea<\/a> and 7% from the northern Brazilian coast<\/a>. A more recent and more northerly study (between Canada and Greenland) from the 2000s led to a 5% recovery rate<\/a>.<\/p>\n

We would expect the results to vary naturally from different experiments in different parts of the world. But to keep things simple, we will stick with 1\/10 as the probability that a bottle with a message is found.<\/p>\n

Now for the second piece of the calculation: of the bottles that are found, what proportion are over 100 years old?<\/p>\n

The table below summarises data from news articles collected on Wikipedia<\/a> about very old bottles with messages that have been found. However, only data on bottles over 25 years old has been collected, presumably because older bottles are more newsworthy.<\/p>\n

So, we needed to estimate the number of 0- to 25-year-old bottles with messages ourselves \u2013 here\u2019s how we did this.<\/p>\n

The table shows that fewer bottles with messages are found as they get older. Messages in bottles degrade over time, which means the bottles have an increased chance of breaking and sinking, or just getting covered in layers of sediment. Plotting this data in the graph below helped us see the trend in the ages of found bottles more clearly.<\/p>\n

We drew a line to match this observed trend in the ages of found bottles. This red line in the graph corresponds to the equation:<\/p>\n

This equation provides an estimate of how many bottles have been found for any specific age range (where 25 = 0-to-25, 50 = 25-to-50 and so on). We are interested in the the 0- to 25-year-old bottles, so the equation suggests 46 bottles have been found in this range.<\/p>\n

Adding up this and all of the numbers in the table gives a total of 106 bottles found, of which 12 are over 100 years old, and 12\/106 is about one in ten.<\/p>\n

Recapping the above, we have that: (A) one in ten bottles with messages are found, of which (B) one in ten are over 100 years old. Bringing these results together using the multiplication rule, we estimate the chance of a message in a bottle being found and it being over 100 years old to be (1\/10)\u00d7(1\/10) = 1\/100.<\/p>\n

So, if there are 100,000 bottles with messages floating around the oceans waiting to be found, we\u2019d expect 1,000 of these to be found and be 100 or more years old. Assuming anybody in the world is equally likely to find one of these, with 8 billion people currently, that\u2019s about a one in 8 million chance of you finding one \u2013 pretty unlikely. <\/p>\n

However, some people are more persistent<\/a> at message-in-a-bottle hunting than others. Following the paths of ocean currents (known as gyres<\/a>) could provide clues on where to look.<\/p>\n

Specifically, peninsulas or islands intersecting with these gyres could be good spots. For this reason, it has been suggested the Caribbean islands are ideally placed<\/a> for finding bottles as they lie on the path of the North Atlantic Gyre. Which seems like a great reason to travel to the Carribean!<\/p>\n

But let\u2019s also spare a thought for the poor soul stranded on their desert island, who surely won\u2019t appreciate the low odds of their SOS being found.<\/p>\n

\"The<\/p>\n

Kevin Burke receives funding from Research Ireland.<\/span><\/em><\/p>\n

David O’Sullivan receives funding from Research Ireland<\/span><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Jenny Sturm\/Shutterstock Recently, a cheerful 100-year-old message in a bottle was found on the south-west coast of Australia. In it, a world war one soldier proclaimed to be \u201cas happy as Larry\u201d. If you\u2019re a betting person, you probably wouldn\u2019t expect great odds of this happening. A bottle cast into the ocean could end up […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-99","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/posts\/99","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/comments?post=99"}],"version-history":[{"count":0,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/posts\/99\/revisions"}],"wp:attachment":[{"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/media?parent=99"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/categories?post=99"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/tags?post=99"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}