Eucalyptus apothalassica is a tree native to New South Wales in eastern Australia.

[2][3]Eucalyptus apothalassica typically grows to a height of around 20 metres (66 ft) and forms a lignotuber.

The leaf blade has a lanceolate to falcate shape and is 5 to 14 centimetres (2.0 to 5.5 in) in length and 0.9 to 3 cm (0.4 to 1.2 in) wide.

It blooms around October and has produces axillary unbranched inflorescences which often are situated near ends of branches in clusters.

[3] The species was first formally described by the botanists Lawrence Alexander Sidney Johnson and Kenneth Hill in 1990 in the work New taxa and combinations in Eucalyptus and Angophora (Myrtaceae) as published in the journal Telopea.