Subglacial rhyolite volcanoes demonstrate an intricate, complex, and poorly-understood connectivity between volatiles, pressure, degassing, and eruptive behaviour. We examine these relationships at different subglacial rhyolitic volcanoes at Torfajökull, South Iceland. Evidence suggests that the eruptive behaviour of these volcanoes appears to be controlled primarily by the variations in initial volatile content, degassing behaviour, and confining pressure. However it has become evident that the final volatile content is not just a reflection of pressure but also of complex degassing processes and eruptive behaviour. Consequently, there remains a substantial challenge in reconstructing the palaeo-ice thicknesses of subglacial rhyolitic eruptions. We report our progress on meeting this challenge.