Arctic sea ice plays a crucial role in the global climate system, acting as both an indicator and an amplifier of climate change. Sea ice mass balance, which is simply the net difference between ice grown and ice melted, is an important parameter that can connect changes in ice thickness to environmental forcings. Opportunities for long-term observations of sea ice mass balance have been greatly expanded by the use of autonomous ice mass balance buoys, which are able to resolve changes to local ice mass balance by measuring time series of snow depth and ice surface and bottom position. This paper presents the design for a newly improved Seasonal Ice Mass Balance buoy (referred to as SIMB-3) that was created to enhance the ability to monitor mass balance with design features that maximize reliability and survivability, reduce installation difficultly, and reduce cost. Operational advancements were also made to make the buoy easy to manufacture, ship worldwide, and assemble in the cold. A custom low-cost datalogger-controller was developed to operate the mass balance sensor package while allowing future expandability for use with non-standard instruments. Several test deployments were conducted in 2018, and the instrument demonstrated ability to successfully collect mass balance data in seasonal sea ice. Results from one of these test deployments in the Beaufort Sea during April 2018, are presented and discussed.