There were a number of plans for amphibious assaults on German islands in the North Sea and even the Baltic coast of Germany, formulated in 1914-15, but these came to nothing as it was chosen to focus on knocking the Ottoman Empire out of the war instead. In 1916-17, planning focused on moves to outflank German lines in Flanders, but these were cancelled due to German coastal defences and the failure of land-based offensives these assaults were to link up with. Finally, in 1918, the RN raided the German-controlled ports of Ostend and Zeebrugge, with the aim of rendering them useless as U-boat bases. For more information on these, see my answers here and here. There were also a number of raids made on targets along the German North Sea coast by RNAS (and later RAF) aircraft operating from seaplane and aircraft carriers, which I've covered here.