School staff believe the hole could be a remnant of the Townley House estate
A three metre-deep sinkhole has opened up on the playing fields of Chatham and Clarendon Grammar School in Ramsgate.
The hole has left staff baffled since it was first discovered when one student's foot fell through the ground as he was playing football around a fortnight ago.
The pit has now grown to approximately one metre by two metres wide and is between 10 and 12 feet deep.
"We will be keeping all children and staff off the field until it has been surveyed. Hopefully by the end of this week we will have an idea of exactly what's happening underground."
Staff do not believe that the opening is a conventional sinkhole, but a long forgotten well or cesspit linked to the Townley House estate.
Teacher Chris Freeman said: "It doesn't appear to be a normal sinkhole, like the one that opened up on the M2 for example.
"It is bad enough that it has stopped our games until we can find out what caused it. Our playing fields have suffered enormous amounts of flooding- they have been saturated since Christmas.
"Some of the school grounds used to be part of the Townley House estate and we believe this could be either a well or an old Victorian cesspit linked to the estate.
A team of geophysical surveyors from Maidstone will inspect the field next week to determine what has caused the hole and whether it poses any further danger.
The school is also checking Victoria era plans of the area to try and solve the mystery of what has actually caused the hole.