FESOM implements the idea of using unstructured meshes with variable resolution. This mesh flexibility allows to increase resolution in dynamically active regions, while keep a relatively coarse-resolution setup elsewhere. FESOM allows global multi-resolution simulations without traditional nesting.

The dynamical core of the original version of FESOM employs the finite element method; its successor, FESOM2, uses the finite volume method, which increases the computational efficiency by a factor of 3-5. Both versions include the Finite-Element Sea Ice Model (FESIM).

Excellent scalability characteristics allow to make effective use of massively parallel supercomputers. 

FESOM is also used as the sea ice-ocean component of the AWI Climate Model (AWI-CM), which will contribute to CMIP6.