The three locks
Watch the gates shut and the water rise as a yacht passes from the lake to the Severn Estuary, the best moment for children.
Until 1999 Cardiff Bay disappeared twice a day. The tide went out, left square kilometres of grey mud behind, and came back to cover it. The calm blue lake in front of you now, roughly 200 hectares of it, exists because of a 1.1 km wall running from Cardiff Bay across to the town of Penarth. It holds back the rivers Taff and Ely, and it is the reason a worn-out coal port became the waterfront you are standing on. The barrage was budgeted at around £120 million; the Harbour Authority puts the final construction bill at £220 million and critics closer to £400 million, and at the time it was one of the biggest civil-engineering jobs in Europe. There is no gate, no ticket and no closing time. The barrage is a public promenade open around the clock, dead flat and without a single step, which makes it one of the easiest walks in the city for a pushchair, a wheelchair or grandparents. Mermaid Quay to Penarth Marina takes 30 to 40 minutes at a stroll. The Millennium Centre and the city skyline sit on one side, the Severn Estuary and the Somerset coast of England on the other. The best moment comes when a yacht arrives at one of the three locks: the gates close, the water rises in front of you over a few minutes, and every child on the barrage ends up leaning on the railing. There is plenty to hold the younger members of the family on the way: a large playground, a skate plaza, an outdoor gym, a small cafe run by the RSPB (the Hafren Cafe), a small free exhibition that for years has been devoted to Captain Scott, who sailed from Cardiff for the South Pole in 1910, and the Enormous Crocodile bench from Roald Dahl (a Cardiff boy), which children queue to be photographed on. A waterbus has in some summers called at the Penarth end, but do not count on it; if you would rather not walk back, the reliable option is the train from Cogan station, a short walk from Penarth Marina, or a bus. An honest word: this is not a sight you give a day to. It is an hour to ninety minutes of air and walking that rounds off a visit to the Bay, and its real value is for families who want space where children can run with no traffic. It is completely exposed, so the wind is constant and can be brutal in winter, and rain has nothing to hide behind; bring a jacket even in August. Parts of it close for a few hours on a handful of days a year for works or ticketed concerts at Alexandra Head, so if the walk is your only reason for coming, check the Harbour Authority site first.
Watch the gates shut and the water rise as a yacht passes from the lake to the Severn Estuary, the best moment for children.
The Millennium Centre and Cardiff skyline on one side, the English coast of Somerset across the estuary on the other.
A big playground, a skate plaza, a small free exhibition and the Enormous Crocodile bench for photos.
Penarth Portway, Cardiff Bay, CF64 1TQ
With small children, do the first half from the Cardiff side, where the playground, locks and cafe are, then turn back; the second half is plain promenade with no facilities. If you walk comfortably, carry on to Penarth and down to its Victorian pier, then return by train from Cogan station, a short walk from the marina, or by bus.
Harsh: constant wind with nothing to break it, frequent rain, dark before five, and no boat link to rely on. A brisk walk in heavy clothes works, but treat it as a short visit, not a family outing.