You will have heard horror stories about people being stung and even killed when they encounter box jellyfish in the sea.

And you may have seen signs saying: "Marine stingers are present in these waters during the summer months".

And you will have had nightmares about bluebottles, those blue jellyfish which appear on beaches and in the ocean where we swim. They don't kill, but they do sting and the sting really hurts.

The deadly types are the box jellyfish and the Irukandji jellyfish but they are confined to the most northern waters.

On the latest figures, at least 69 people have died since records began in 1883. That's about one every two years - which does not make the risk great.

But non-fatal stings are numerous - and very unpleasant.

According to the The Royal Australian College of General Practitioners, "There are around 10,000 cases of bluebottle stings on the east coast of Australia each year."

How great the pain is depends on how much of the jellyfish's tentacle touched the bather's skin and how much of the venom was released. The pain is severe but fades after about an hour. There will be a red line where the tentacle touched.

Let's start with what not to do.

It is not true that urinating on a jellyfish sting can ease the pain. It may do the opposite.

Here's Scientific American, no less: "Unfortunately, in the real world treating a jellyfish sting by urinating on it may actually cause even more pain, rather than relief. Urine can actually aggravate the jellyfish's stingers into releasing more venom. This cure is, indeed, fiction."

Do not do it.

The myth may have come from the American series Friends where, in an episode in 1997, the friends went to the beach.

One of the characters, Monica, was stung by a jellyfish and Joey remembered seeing a documentary in which the advice was to urinate on the sting. Monica's pain eased. The mis-remembered "remedy" worked.

But that was fiction - a drama which got the science wrong.

The Australian Museum says: "Our urine can either be acidic or alkaline, and when the latter, could make the sting worse by stimulating more stinging cells to be released. Freshwater should also not be applied to the sting for the same reason."

And remember: there is always someone there to film you on their phone.

The Royal Australian College of General Practitioners advises: "The person should leave the water immediately. If there is a significant sting to the face or neck, or if there are signs of severe illness (eg. breathing difficulties), an ambulance should be called by dialling 000.

"Any tentacles that remain stuck to the skin should be removed, either by using tweezers or by hand (while wearing gloves). The site of the sting should then be washed with seawater."

The victim should try not to move because moving may worsen the pain. Don't rub the hurt part because that may prompt more of the venom to be released.

Know, too, that the pain will go away after about an hour.

The director of Australian Marine Stinger Advisory Services, Dr Lisa-ann Gershwin, told this paper that rinsing with sea water was really important to remove the "stinging cells which haven't released their venom".

It might be tempting to use cold water but that may make it worse because coldness promotes the spread of the venom.

The GPs' association advises: "Hot water immersion can be applied after initial treatment, but to be effective, heat needs to be applied as soon as possible after stinging.

"Apply hot, but not scalding, water (ideally at 42-45°C), or a heat pack for 30-90 minutes or until the pain resolves." This can be done, they say, via:

The nastiest types of jellyfish inhabit the waters around the northern parts of Australia - Queensland, the Northern Territory and the north coast of Western Australia.

After a girl died from a sting from an Irukandji jellyfish at Bamaga in the far north of Queensland, Surf Life Saving Queensland advised people to wear a full-body Lycra suit.

But the more likely problem is the bluebottle.

The good thing is that they, unlike lots of jellyfish, are very visible, so don't go in the sea if you spot them either in the water or on the beach, Dr Gershwin said.

And you are likely to spot them. "They come with their own warning system. It's a beautiful blue. It's a loud, blaring colour which gets your attention," the jellyfish expert said.

They are not solitary creatures. "You don't get one. You get an entire armada, saturating the beach.

"If they are on the beach, they are in the water," she said.

There are basically three parts to them: the blue bubble which sits on the surface and acts like a sail, a small sack just below the surface and then the tentacles which hang down in the sea water in the hope of stinging fish.

Bluebottles are completely at the mercy of the wind. If a beach is north facing and the wind is coming from the north, the beach - and bathers - are more likely to get bluebottles.

The trick is not to get stung in the first place. If they're in the water, it's best for you not to be.