Why Do Cherries Float in Water?
Cherries float in water because they are less dense than water, and the reason for that is mostly air. A cherry is about 80% water by weight, but it also contains air pockets trapped between the flesh and the pit, and in the spongy tissue at the stem end. Those air pockets lower the overall density of the fruit enough to keep it at the surface. The same principle explains why unpeeled oranges float and why a lemon floats but a lime sinks.
The floating test is more than a curiosity. It is a useful quality indicator in the cherry industry and at home. Cherries that float are usually fresh and in good condition. Cherries that sink are sometimes overripe, waterlogged, or have damage that has allowed water to penetrate and replace the internal air. This is not a hard-and-fast rule — some perfectly good cherries sink — but as a general tendency, floating is a positive sign.
The Buoyancy Science
Buoyancy is determined by Archimedes' principle: an object floats if it displaces a weight of water equal to or greater than its own weight. Water has a density of 1 gram per cubic centimetre. A cherry's density depends on its composition: the water content (density ~1), the sugar content (denser than water), the pit (denser than water), and the trapped air (much less dense than water). For a cherry to float, the overall average density of all these components must be less than 1.
Most cherries land just under that threshold. The air pockets are the deciding factor. When a cherry is fresh and its skin is intact, the air stays trapped inside and the fruit floats. If the skin is damaged or the fruit has been sitting in water long enough for water to seep in and displace the air, the cherry becomes denser and sinks. This is the same reason an unpeeled orange floats — the porous rind traps air — but a peeled orange sinks because you remove the air-filled rind. See our orange buoyancy guide for that explanation.
The Cherry Industry's Float Test
Cherry growers and processors use water flotation as a routine part of grading. After harvest, cherries are dumped into tanks of water. The floaters are skimmed off as top-grade fruit. The sinkers — which are typically overripe, damaged, or waterlogged — are separated out for processing into lower-value products like pie filling or juice. The float test is fast, non-destructive, and surprisingly effective at separating good fruit from bad.
This is particularly important for cherries destined for the fresh market, where appearance and firmness matter. A sinking cherry in a processing tank is not necessarily unsafe to eat — it just means the fruit has lost some of its internal air, which usually correlates with being softer or older. If you buy a punnet of cherries and a few sink when you wash them, those individual cherries may still be fine to eat, but they are likely riper or softer than the floaters.
The Stem-End Air Pocket
One of the key air reservoirs in a cherry is at the stem end. When the cherry is attached to the tree, the stem connects to the fruit through a small opening. After the cherry is picked, that opening partially closes but does not fully seal. A small pocket of air remains in the spongy tissue just inside the stem attachment point. If you cut a cherry open right at the stem end and look carefully, you can see this spongy, slightly whitish tissue. It is the same structure you see in apples and pears around the stem.
This air pocket is one of the reasons the stem comes out so easily on an overripe cherry. As the fruit softens, the tissue around the stem breaks down, the air pocket enlarges, and the connection weakens. A fresh cherry holds its stem tightly. A cherry that drops its stem when you barely touch it is past its prime. This is one of the freshness tests you can do in the shop before buying.
How to Use the Float Test at Home
If you have a punnet of cherries and want to sort the best from the rest, fill a bowl with cold water and drop the cherries in. The floaters are your top-tier fruit — eat those raw or use them where appearance matters. The sinkers are softer and riper — use those for cooking, baking, or jam where texture is less important. Neither group is unsafe unless there is visible mould, leaking juice, or fermentation smell.
Do not leave the cherries in the water for long. Cherries absorb water, and prolonged soaking will make them split. Split cherries are still edible but do not store well. Rinse them, float-test them, and take them out within a minute. For longer-term storage, keep cherries unwashed in the fridge in a breathable bag. See our storage guide for details.
Other Fruit That Floats
Cherries are not the only fruit that uses the float test. Apples are graded by density in some packing houses — floaters are fresh and crisp, sinkers are mealy or bruised. Oranges and lemons float because of their porous rinds. Grapes float, although not as reliably as cherries. Watermelons float, and the float test is one of the ways the industry estimates maturity — see our watermelon ripeness guide for more on how watermelon density relates to ripeness.
The common thread is trapped air. Any fruit with a rind, skin, or internal structure that traps air will tend to float. Fruits with denser flesh and less trapped air — like a ripe peach or a mango — will tend to sink. The exact behaviour depends on the variety, ripeness, and water content, but the principle is the same.
Do All Cherries Have Pits?
This comes up a lot because people worry about the pit when eating cherries. Yes, all naturally occurring cherries have pits — there are no pit-free cherry varieties. The pit is the seed of the cherry fruit, and it is also one of the denser components of the cherry, which means it contributes to sinking. A pitted cherry floats more reliably than an unpitted one because removing the dense pit lowers the average density. See our cherry pits guide for how to pit cherries with and without a pitter, and for what to do if you swallow one.
Buying the Best Cherries in Australia
Australian cherries are at their best from November to February, with the peak in December. The season is short — about six weeks in most growing regions — so when they are in, buy them. Young in New South Wales and Tasmania produce the best fruit. Look for firm, glossy cherries with green, fresh-looking stems. Scan the punnet with PickFresh if you want a freshness score before buying. And for when to expect them, check our cherry season guide.
Frequently Asked Questions
Cherries float because they are less dense than water. About 80% of a cherry is water, but the remaining 20% includes air pockets trapped in the flesh and at the stem end. This trapped air lowers the average density enough to keep the cherry at the surface.