Why Do Dolphins Jump, and Are They Really Smiling?

So why do dolphins jump, and do they really smile? The short answer: the smile is only the shape of the face, and a jump can mean many things, from travelling to talking to shaking something off. Joy is one possible answer, and often not the main one. The longer answer is more interesting, and it has changed how I watch dolphins from a boat.

Dolphins have to come up for air, on purpose

Dolphins are mammals. They have no gills, so they breathe air, and every few minutes they come up for a breath. Unlike us, they do not breathe on autopilot. Researchers who study dolphin sleep describe a pattern called unihemispheric sleep, where one half of the brain rests while the other half stays active. The usual explanation is that the awake half lets the animal keep surfacing to breathe. I am giving you the general scientific view here, not a detail I could measure myself.

This matters for us because a dolphin’s rest is never total. A resting dolphin is still swimming, still breathing and still watching. When a boat comes close, the awake half of the brain notices.

The smile is only the shape of the face

The curved line of a dolphin’s mouth is a permanent feature of its head and jaw. It does not change with mood, the way a human smile does. I could not find a formal study that tests this, so I share it as the general view of marine biologists. A dolphin that looks happy to us may be tired, stressed or afraid, and its face will look exactly the same.

I think this is the hard part for us humans. We read faces very well, and a dolphin face reads as friendly. So we trust the face, when we should be reading the behaviour: the speed, the direction, the spacing of the group and the breathing.

Why do dolphins jump?

The best-known researcher of spinner dolphins, Ken Norris, wrote that spins and other aerial displays are probably used “to mark the dimensions of the school”, a way of telling the group where everyone is. Another old idea, first proposed in 1963, was that spinning knocks off remoras, the sucker fish that attach to dolphins. A 2006 model suggested a spin could produce enough force to do it. But a later study by Duke University in Hawaii found that spinning leaps were not statistically linked to whether a dolphin had a remora. So that explanation is now doubted, and scientists keep several ideas open.

One thing is certain: a big leap costs energy, so it is not free fun. It can also be a reaction. A school that leaps beside the boat, or swims fast ahead of it, may simply be moving away. From the outside, a flight and a party can look very similar.

Resting dolphins and the 50-yard rule in Hawaii

Spinner dolphins in Hawaii feed offshore at night and come into sheltered bays by day to rest. Because those bays are also where people go to swim, NOAA decided that distance was needed. Since 28 October 2021, a federal rule prohibits swimming with, approaching or staying within 50 yards (about 46 metres) of Hawaiian spinner dolphins, within two nautical miles of the main islands. There are exceptions, such as moving away promptly if a dolphin comes to you by itself. If you travel to Hawaii, check the current rule before you go.

Hawaii is not Bali, and I will not pretend that the same rule applies to every dolphin in the world. The dolphins of Lovina, in Bali, may follow a similar daily rhythm, and many people believe they do, but I did not find a study that proves it there. You can read more in our Lovina dolphin guide and in our story about noise and crowds in Lovina.

Why the babies work so hard

I have to be careful with the idea that “calves get tired”, because the science is more subtle than that. A newborn dolphin has to keep up with its mother from the first hours of life, swimming close beside her. In a study that followed three dolphin mother and calf pairs from birth, resting at the surface disappeared completely for at least the first two months. They keep moving, and they keep watch. That is a very busy start in life, and it leaves little spare energy for extra detours.

Boats add to that. In a 2020 study from Bocas del Toro, in Panama, researchers followed bottlenose dolphins for ten weeks in 2014 near a bay with many tour boats. When boats were present, the dolphins were less likely to keep socialising and more likely to switch to travelling, and less likely to start foraging while travelling. The authors argue that these changes probably have energy costs for the dolphins, which could add up over time. They did not measure the costs themselves, so I say “probably”, as they do.

I could not confirm a published figure for how much more tired a calf gets near an engine, and I do not want to invent one. What the evidence supports is gentler and, I think, enough: a small calf that has to keep swimming away from boats has less room for feeding, resting and staying close to its mother.

How to watch dolphins kindly

Choose a boat that keeps a wide distance, stays out of a crowd of boats and never chases or circles. Ask the captain to switch off the engine or idle when dolphins are near. If a school turns away or swims off, let it go. A short, calm meeting from a distance is a good meeting. Our list of warning signs on dolphin tours will help you choose. Wildlife encounters are unpredictable. Dolphin watching should always follow local regulations and experienced professional guidance.

If you want to film, a small action camera on a strap lets you keep your hands free and your body inside the boat, and a roll-top dry bag keeps phones and papers dry on a sea morning. Neither will give you a better dolphin day than patience will.

Where Ocean Calling stands

We watch wild dolphins from the boat and never chase, feed or touch them. You can read more about the dwarf spinner dolphin in our Ocean Atlas. Groups are small, with a maximum of six guests, and nobody has to get into the water to have a good day. If this made you curious about experiencing it yourself, you can explore our retreats.

Questions people ask

Do dolphins really smile?

No. The curved mouth is the shape of the jaw and does not show how the dolphin feels. To understand mood, watch behaviour: speed, direction, spacing and breathing.

Why do dolphins jump out of the water?

There is no single answer. Scientists suggest travelling, communicating, marking the size of the school, play, courtship and sometimes avoidance. The idea that spinning removes remoras was tested in Hawaii and did not hold up well.

How often do dolphins need to breathe?

Every few minutes they come up for air. They breathe by choice, not on autopilot, and they rest with one half of the brain at a time.

Do boats really tire dolphin calves?

I cannot say “tire” as a measured fact. A 2020 study in Panama found that tour boats changed dolphin behaviour, with less socialising and foraging and more travelling, and the authors expect an energy cost. Mother and calf pairs have little spare energy in the first months.

Is it legal to swim with wild dolphins?

It depends on the country. In Hawaii, since 2021, it is not allowed to swim with or approach spinner dolphins within 50 yards. Other places have different rules or none. Check the current rule before you travel.

What is the kindest way to watch dolphins?

From a boat that keeps its distance, slows down and never chases, with a crew that lets the dolphins leave. A short calm meeting is better than a long chase.

Wildlife encounters are never guaranteed and never forced. Ocean Calling works only with vetted, ethical local operators, and every animal is free to approach, or not, entirely on its own terms.

Sources & further reading

1. Swim With and Approach Regulation for Hawaiian Spinner Dolphins, final rule (Federal Register, 28 September 2021) NOAA Fisheries, 2021.
2. New regulation protects Hawaiian spinner dolphins against disturbance NOAA Fisheries, 2021.
3. Tour boats affect the activity patterns of bottlenose dolphins (Tursiops truncatus) in Bocas del Toro, Panama (Kassamali-Fox et al.) PeerJ 8:e8804, 2020.
4. Sleep behaviour of dolphin mothers and calves (Lyamin and colleagues; PDF hosted by UCLA) Nature / UCLA, n.d..
5. Temporally and spatially partitioned behaviours of spinner dolphins: implications for resilience to human disturbance PubMed Central, 2017.
6. How Dolphins Spin, and Why Live Science, n.d..
7. Spinner dolphin aerial behaviour and remora removal (Utley) Duke University, 2014.

Further reading on Ocean Calling: Noise and crowds at Lovina · Lovina dolphins: what to know before a sunrise boat trip · Dolphin tour warning signs