The island belongs to the National Trust and is therefore accessible, unlike most of the tidal islands in Strangford Lough which have Private, Keep Out notices on their bridges and causeways or the lanes leading to them. However you cannot access it the easy way via the causeway that links it to the mainland, as there is no public access down the driveway that comes off the Newtownards Road half a mile west of Greyabbey. It is however accessible across the sands at low tide. I parked in the car park on the southern edge of Greyabbey just off the A20 Portaferry Road. The noticeboard in the car park says "Easily accessible at low tide, Mid Isle is a 15 minute walk across the sands from this car park." Well it was an easy walk and you can't get lost but it was more of a paddle than a walk, although the water wasn't deep enough at any point to come over the top of my walking boots. There are a couple of shallow channels of water to cross on the way but the sand seemed firm enough all the way across. The noticeboard reassured me because it didn't mention soft mud or quicksand. I crossed about 2.5 hours before low tide and the sands had obviously been clear for a while by then.
There is one cottage on the island. It is not currently inhabited but was previously home to the shore steward for the Montgomery Estate and the home for many generations of the McAvoy family. It is apparently a classic 19th century Ulster cottage.
After my visit 2 separate people mentioned that Brad Pitt had been on Mid Island the previous week filming some scenes for the film The Lost City of Z, which he is directing. Interesting though it would have been to see a film set I am sure they wouldn't have allowed me anywhere near the island while they were filming, so I was glad they had all departed. There was little sign that a whole group of people had been there. The track across the island had some recent ruts in it but that was all. There was an old jeep type of vehicle near the cottage but I didn't see anyone else on either Mid Island or the neighbouring South Island.
Part of Mid Island is covered in mature trees - sycamore, ash, conifers, beech and alder. There is a fenced off field at the southern end but there no animals grazing it at the time of my visit in early September 2015. The island is roughly oval in shape and is about 400 metres from north to south and 300 metres from east to west. It is a bit higher in the centre of the island than at the edges but nowhere on the island is more than 10 metres above sea level. Along the shoreline sea mayweed and sea lavender were in flower and I also spotted samphire. There were also several blackberry bushes on which I feasted.
Cottage on Mid Island
Causeway to the mainland
Cottage on Mid Island
Hut - I have no idea for what this is used
Grazing field on Mid Island - there was no livestock there at the time of my visit
Mid Island from South Island