The service to England soon became a weekly one, while there are at least three weekly sailings to the United States.
London and other English ports, French, Italian and Levant coast towns are also served by passenger steamboat sailings from the two great North Sea ports.
Harlingen has become the most considerable seaport of Friesland since the construction of the large outer harbour in 1870-1877, and in addition to railway and steamship connexion with Bremen, Amsterdam, and the southern provinces there are regular sailings to Hull and London.
Apart from coasting trade there are constant sailings to the leading European ports, the United States and the British colonies.
Belfast is connected by daily sailings with Glasgow, Ardrossan, Liverpool, Feetwood, Barrow and Heysham Harbour, Dublin with Holyhead and Liverpool, Greenore (Co.