Near the icecaps in West Greenland is a glacier lake without any visible surface outflow.
This lake has one of the biggest icebergs of any lake in the world. The biggest I have measured calved in 2016 and was 1km long, 200m wide and 120m in height. The height is estimated from an image in 2017 after the iceberg turned over. Other icebergs in the lake are similar in size, several reaching 300-600m in length. The whole front of the glacier retreated over 100m from August 2016 until August 2017.
The lake itself is 15 km W-E, 10.5 km N-S and at least 120m deep (otherwise the icebergs can't turn over). According to Google Earth and Greenland Bedrock Map the lake is at 800m above sea level. Maybe it has an outflow beneath a glacier, but I can't say under which one, the bedrock data isn't accurate enough. It should be a good place to study non-ocean terminating glaciers. If the ice sheet retreats further inland it might expose more lakes, which don't have warm ocean water to melt the glaciers from beneath and can't transport icebergs away.
On Google Earth/Maps this lake doesn't even exist and just shows as white snow unless you zoom really close. I'm not sure if it has a name, but feel free to reference it or any of the glaciers terminating in it.
The actual center of the lake is 66N, 55.15W, but in a few years it will melt the ice sheet and reach 50W.