Skip to main content


The EM 304 MKII is the successor of the highly acclaimed EM 302 and the EM 304 MKI.
Its broad range of functionality supports simultaneous collection of multiple data types, saving time in the planning, execution and analysis phase. The low noise echo sounder delivers superior data which requiring minimal post-processing.

With its broad frequency span the systems sets a new standard in the market with no compromises between range and resolution. The EM 304 MKII can map the shallow-to-medium water depths with high resolution and still map the deepest depths with a good coverage. Compared to the EM 304 MKI the MKII will have an increase of 75% swath performance at 6000m.


The EM 304 MKII uses state-of-the-art electronics and separate transmit and receive transducers in a Mills Cross configuration. It utilises field-proven electronics and transducer from the EM 304 MKI/EM 302 making for an easy upgrade.
The design is highly, modular and flexible with compact electronics for easier and faster installation. The flexible transducer design make it possible to tailor the system to almost any required size.
Ultimate system performance – resolution and range – is achieved with the largest standard size, 0.3 x 0.5 degrees. The smaller 4 x 4 degrees solution can be installed on any vessel of opportunity.


Acoustic ice protection windows can be offered for vessel going to the ice rand and for ice breakers. Both TX and RX icewindows are made of hyperlast reinforced with titanium rods proven to withstand surveys across the North Pole.
The transmit fan can be divided into >16 individual sectors (dual swath mode). This gives a unique control and enables active real-time stabilisation to correct for yaw and pitch vessel movement. Roll stabilisation is applied on the receiving beams. The result is a stabilised system, full ensonification of the seabed with an equally distributed footprint in all types of weather conditions leaving no gaps or holes in the mapped area.
Beams are maintained and automatically adjusted according to achievable coverage or operator defined limits. Up to 1600 individual beams are available in dual swath mode.
The two individual transmitting fans are generated with a small difference in tilt to provide a constant sounding separation along track. The result is a dense sounding pattern on the seafloor.


The system produces a strong dampening of multi-bounce interference from false echo, resulting in significantly cleaner data. Near field beam focus is applied in real time during transmission and reception. The result is a much higher resolution representation of the seabed.


The EM 304 MKII is part of the new EM platform designed for future challenges and uses the new datagram format. The format supports several new features, such as extended backscatter calibration, with more features already in development. The new platform is supported by Kognifai, KONGSBERG's open digital ecosystem bringing opportunities to transform survey operations through digitalisation.
Like all KONGSBERG EM multibeam echo sounders, the EM 304 MKII ensures the best operating environment to safeguard marine life inhabiting the survey area, through decreased emitted sound levels.

Realtime Software

Post Processing software

Note: KONGSBERG is not responsible for any system malfunction caused by 3rd party software.

If you would like to be informed when a software update is available, please click here to sign up to the mailing list.

Services and support

  • 24/7 Technical support

    Our 24/7 technical support team is there to help at any time, day or night, wherever your vessel is.


    We understand the importance of having the right parts, available in the right place, at the right time.

  • Training

    Ensure that your crew is properly and thoroughly trained. This will reduce operational risk, downtime and maximise return on asset investment.

How can I help you?

Helge Uhlen
Vice President Underwater Mapping