One of the busiest shipping areas in the UK will be able to accommodate "super-sized container vessels" after dredging plans were approved.
Harwich Haven Authority (HHA) wants to increase the depth of Harwich Harbour and its access channel.
The HHA looks after an area including the ports of Felixstowe in Suffolk and Harwich International in Essex.
Neil Glendinning, chief executive of the authority, said the development was "critical" to the economy.
The project, approved by the Marine Management Organisation, is scheduled to start in 2021.
The work could cost up to £100m and would take 18 months to complete.
The authority said deepening the channel would allow "almost unrestricted access" to the ports in the area, which also include Ipswich and Mistley.
It said the plans would "futureproof access for the growing numbers of super-sized container vessels currently in operation and new vessel builds under construction".
The authority said 40% of the UK's container traffic currently passes through the area, and the plans followed "extensive environmental studies".
The depth of channel will increase by 1.5 metres, with the trend in commercial shipping to increase the size of container vessels to reduce movements of ships, the HHA said.
Mr Glendinning described the planned improvements as "significant".
"The global ports sector is increasingly competitive and will become even more so post-Brexit, so it's vital that port operators in the Haven can compete," he added.