Regular ferry services run between Picton in the Marlborough Sounds and Wellington, operated by KiwiRail (the Interislander) and Strait Shipping (Bluebridge). Both companies run services several times a day. Roughly half the crossing is in the strait, and the remainder within the Sounds. The journey covers and takes about three hours. The strait often experiences rough water and heavy swells from strong winds, especially from the south. New Zealand's position directly athwart the roaring forties means that the strait funnels westerly winds and deflects them into northerlies. As a result, ferry sailings are often disrupted and Cook Strait is regarded as one of the most dangerous and unpredictable waters in the world.