Historic maps from 1838 show the castle occupying a tiny peninsula that jutted into the northern side of the lake, measuring roughly 55 to 60 metres in both directions. Today, the lake has long since been drained, leaving the castle ruins overlooking flat reclaimed pasture land, some of which has been planted with coniferous forest. By 1929, the Ordnance Survey maps had already downgraded the site from ‘Ballinteean Castle in Ruins’ to merely ‘Ballinteean Castle (Site of)’, suggesting significant deterioration even by that time.

What remains today are the grass-covered stone footings of a rectangular building at the eastern end of an elongated rise. The main structure measured approximately 10 metres east to west and 7 metres north to south, with a smaller square room, about 4.4 by 5 metres, attached to its eastern side. The walls vary considerably in their preservation; some sections are barely 30 centimetres high whilst others reach nearly a metre. The most substantial remnant is the dividing wall between the two spaces, which forms a grass-covered mound about 2 metres wide and up to a metre high, with masonry still visible protruding through the vegetation in places.

About 10 metres west of these main ruins, a curious sunken rectangular depression can be seen in the ground, measuring roughly 9.6 by 5.7 metres. Its purpose remains unclear; it could be the remains of an earlier structure, a later addition, or perhaps something entirely unrelated to the castle itself. The whole site offers a glimpse into how dramatically the Irish landscape has changed over the centuries, from medieval fortification on a lake peninsula to lonely ruins in reclaimed farmland.