The N21 is a proposed national route in the City of Cape Town, South Africa.

[2] A number of environmental impact studies have been done, to determine whether new sections of the freeway will upset the delicate ecological systems in the Cape Town area.

[6][7] The Peninsula Expressway will have junctions with three National Roads, the N1, the N2, and the N7 as well as the M3 and the M5 which are Cape Town metropolitan freeways.

[8][6][1] In August 2022 the Western Cape Department of Transport and Public Works announced the launch of an environmental impact assessment for the extension of the R300 from its current terminus at the N1 northwards to the R302 (Wellington Road).

[9] The project to extend the R300 has been opposed by some members of society due to them wanting to preserve the areas in which the proposed road is meant to pass (such as wetlands and sanctuaries).