Port Arthur tours, ruins by the sea.

Port Arthur, Australia is, in the words of the authority that runs it, the largest and most intact convict settlement in Australia and a key part of the World Heritage-listed Australian Convict Sites. Discover Tasmania records that about 12,500 convicts served sentences there between 1830 and 1877. Today the three Port Arthur Historic Sites belong to a World Heritage listing of eleven places, inscribed in 2010.

Its position was deliberate. The site says the colony was placed here for its naturally deep and sheltered harbour, and that cold sea, thick forest and 300-metre cliffs made the place a natural prison. Stand on the lawn below the Penitentiary and both halves of that story are in front of you: a lovely bay and a place built to hold people. The contrast is the first thing guests remark on, and it never quite wears off during the day.

The settlement even built its own ships: the site ran a Dockyard from 1834. Across the water, Point Puer held boys, and the site describes it as the first purpose-built juvenile prison in the British Empire. Every corner of the grounds carries a story of that kind, and the guides bring those stories to life on the day. Ask yours about the boys of Point Puer as the boat passes their old prison.

On weekdays the itinerary offers an optional 30-minute visit to Remarkable Cave before the chocolate stop. Discover Tasmania describes a descent of 115 steps to a platform at the foot of sandstone cliffs, looking through the tunnel to the Southern Ocean. On a big swell day the sound of the sea in the rock is the thing you remember.

It is a short, steep detour after a long walk around the site, so judge your legs. In the newest reviews, guests chose to skip a coastal stop and spend the time at Port Arthur instead, and the guide let them decide. Others are glad of the fresh air after hours among stone walls. That flexibility is worth asking about on the day. It matters most when the weather turns and a dry hour among the museum houses looks more inviting than wet steps.

The cave belongs to Tasman National Park, where the Parks and Wildlife Service describes dolerite spires and sea-carved sandstone along the whole coast. A parks pass is required to enter national parks, so if you return with a car, buy one first. On the tour itself, the guide handles the logistics and the timing.

Port Arthur sits on the coast in the far south-east of Tasmania, and its weather changes fast. It is the kind of place where you can see sun, rain and wind inside the same hour. The site warns that UV can be very high in summer even under cloud, that spring brings wind and that winter calls for layers. A bright morning in Hobart can turn into a grey, breezy afternoon at the site, and the other way round.

The weather station at Palmers Lookout, 2.5 km from the site, gives an average high of 18.8 °C in January and 11.3 °C in July. Daylight in mid-June lasts only 9 hours, so a winter day ends early. The coach leaves before dark, but the walk around the grounds is cooler than the numbers suggest when the wind comes off the harbour. Summer brings long evenings and far more daylight for the drive home.

Dress in layers, with a raincoat and sturdy shoes, as the site recommends, and add a warm layer for the boat. A beanie folds into a pocket and weighs nothing. Umbrellas are of limited use in the wind on this coast. Pack sunscreen and a hat in summer, whatever the sky looks like in Hobart. The gift shop sells ponchos if you are caught out.