Europe's total offshore wind capacity increased by 25 percent in 2017, according to WindEurope.
Just over 3.1 gigawatts (GW) of new offshore wind was installed in Europe last year, with total capacity hitting almost 15.8 GW, according to the trade body.
WindEurope CEO Giles Dickson described the 25 percent increase as "spectacular" and said that offshore wind was now a mainstream part of the power system.
"The costs have fallen rapidly," he said. "Investing in offshore wind today costs no more than in conventional power generation."
Europe is now home to more than 4,000 offshore wind turbines across 11 countries. Thirteen new offshore wind farms were completed in 2017, with the U.K. and Germany accounting for the majority of these. The U.K. installed 1.7 GW of offshore wind, while Germany was responsible for 1.3 GW.
Last year also saw the world's first floating offshore wind farm, Hywind Scotland, begin to send electricity to the Scottish grid. The 30-megawatt farm, which can be used at water depths of up to 800 meters, is operated by Statoil in partnership with Masdar.
Looking ahead, 11 offshore wind farms are currently being built; these will add an extra 2.9 GW once completed. This "project pipeline" should give Europe 25 GW of offshore wind capacity by 2020, WindEurope said.
"We'll see further growth in 2018 and 2019," Dickson said. "But the longer term outlook for offshore wind is unclear. Very few countries have defined yet what new volumes they want to install up to 2030."