A pond barrow inverts that logic. Rather than a heap of earth raised over the dead, it presents a shallow circular depression ringed by a bank, the whole thing reading as a wide, saucer-shaped bowl pressed into the landscape. The example at Seefin in County Mayo sits on level elevated ground with open views in most directions, and to walk around it is to feel slightly uncertain about what you are looking at. The interior is not dramatically lower than the surrounding field; the effect is subtle, almost geological, until the enclosing bank resolves itself and the geometry becomes clear.

Pond barrows are a rare monument type, more commonly associated with the Bronze Age concentrations of southern England than with the west of Ireland, which makes the presence of one in Mayo quietly significant. The earthen bank here measures roughly 25 metres east to west and 24.5 metres north to south at its crest, and it is far from slight. On the southern side the external face rises to about 1.6 metres and the slope extends around 8 metres outward, giving it a more pronounced profile than the northern side, where the external height drops to 0.85 metres. The inner slope merges with the interior in a continuous broad descent of around 10 metres, producing that characteristic saucer shape. Scattered stones along the bank's top and inner face, and a few more across the soft, wettish centre of the interior, suggest the structure may once have had a more substantial stone element, though whether these are the remnants of something deliberate or simply field clearance is not easily determined. A low break in the bank at the southeast may mark an original entrance, though this is uncertain.

A field wall, which also follows the townland boundary, cuts across the enclosure on a roughly north-northeast to south-southwest line, slightly east of centre, and hawthorn, ash, and sycamore trees have taken root along it over time. The enclosing bank itself is fringed by hawthorn and gorse, which in practice means the monument is easier to read from a little distance than from close in.