More than 3,400 people have died in the Mediterranean this year trying to get to Europe.
The UN refugee agency says most set off from Libya heading for Italy or Malta to look for work or seek asylum.
It also says more than 200,000 people managed to make the risky sea crossing, often fleeing conflict or persecution.
That is almost three times as many as the previous high, recorded in 2011.
UNCHR says Europe is experiencing a large number of sea arrivals due to conflicts in Libya, Ukraine, Syria and Iraq.
Worldwide, the organisation has received reports that 4,272 have died attempting to make crossings.
UN High Commissioner for Refugees António Guterres says some countries are prioritising keeping people out instead of upholding asylum. "This is a mistake," he warns, "and precisely the wrong reaction for an era in which record numbers of people are fleeing wars.
"Security and immigration management are concerns for any country, but policies must be designed in a way that human lives do not end up becoming collateral damage," he adds.
