Monaco: Monaco's Oceanographic Museum will both enchant and revolt

An unwanted visitor from Australia lurks inside the Oceanographic Museum in Monaco. White-spotted jellyfish hitched a lift from Queensland to the Mediterranean in ship's ballast in the 1960s and have since been doing rather well in their new environment. Their descendants float about, stinging unsuspecting swimmers off Spanish beaches and threatening native shrimp.

The white-spotted jellyfish in the museum's aquarium is rather beautiful though, resembling a placid, floating pincushion of vivid white dots. It has the trailing, feathery skirts of a can-can dancer. Not so attractive is the jellyfish's sex life. Males release sperm in the water and females gather it into their mouths, where they hold eggs until they hatch.

If you want to be alternatively enchanted and revolted, then Monaco's Oceanographic Museum is the place to be. It's the principality's unexpected treat, at once a serious scientific research centre, an entertainment and an education. Founder Prince Albert I was a scientist and oceanographer, and Jacques Cousteau was once director. It has cutting-edge displays, yet parts are endearingly old fashioned, hearkening back to the days when Edwardian-era aristocrats had unlimited budgets and a liking for the weird and wonderful.

The 1910 neoclassical museum building is Monaco's most prominent structure. Many mistake it for the palace. It looms on a clifftop like the mad retreat of a James Bond villain, with a facade encrusted with motifs of crabs and scorpionfish and octopus. Its main hall is a magnificent cabinet of curiosities from another era. You can clamber into a 1776 Bushnell Tortoise submarine, which resembles a giant wine barrel with a screw cap. There are strange diving suits, a stuffed polar bear, sea fossils, ship models and marble busts.

In the Whale Room, gigantic skeletons dangle from the ceiling. They look like dinosaurs and have open jaws of serrated teeth. The narwhal brandishes a javelin-like horn. Touch screens below tell you more, and an hourly sound-and-light show entrances kids.

There are some 6000 live specimens, too. This is one of the world's oldest aquariums. A moray eel acquired in 1969 is still alive and well, and some sharks and other fish are 40 years old. There have been tropical tanks here since the 1930s, and Monaco was among the pioneers of the delicate task of keeping notoriously temperamental coral in artificial environments.

Its centrepiece is a 450,000-litre tank holding an entire coral ecosystem. Some of its corals are now 20 years old, a first in the history of aquariums. The most stunning display is a pool of fluorescent coral, including luminous purple and pink Montiposa, waving green Galaxea and lurid Blastomusa that look like 1970s lava lamps.

The Shark Lagoon is rather grey in comparison, but its creatures are splendid. There are several types of shark, rays, a rather lonely hawksbill turtle and an outsized guitarfish that looks like a stealth bomber from the distant future. The kids can touch a baby shark and shark's eggs at the touch tank, as well as crabs and starfish. If you've never seen a shark's egg before, you'll be astonished.