A system for isolating a wellbore having a fluid flow passage extending from surface to a subterranean location, the system comprising: a first, downhole, valve member configured for location in the wellbore at a first subterranean location and moveable between a first configuration which permits access through the flow passage and a second configuration which isolates the flow passage below the first valve member ; a second, uphole, valve member configured for location in the wellbore at a second subterranean location spaced from the first valve member and moveable between a first configuration which permits access through the second valve member and a second configuration which, when the first valve member defines the second configuration, provides an isolated volume between the first and second valve members (20,22;120,122); a monitoring arrangement for obtaining information relating to a condition in the isolated volume ; and a communication arrangement for communicating the information relating to the condition in the isolated volume to a remote location, wherein the communication arrangement is configured to transmit or otherwise relay the information relating to the condition in the isolated volume to the remote location via at least one intermediate location, wherein the at least one intermediate location comprises a first intermediate location located at a subterranean location in the wellbore uphole from the second valve member, the communication arrangement comprising a first receiver/transmitter or transceiver disposed at the first intermediate location, wherein the communication arrangement comprises a wireless communication arrangement configured to transmit or otherwise relay the information relating to the condition in the isolated volume to the first receiver/transmitter or transceiver wirelessly. a first, downhole, valve member configured for location in the wellbore at a first subterranean location and moveable between a first configuration which permits access through the flow passage and a second configuration which isolates the flow passage below the first valve member ; a second, uphole, valve member configured for location in the wellbore at a second subterranean location spaced from the first valve member and moveable between a first configuration which permits access through the second valve member and a second configuration which, when the first valve member defines the second configuration, provides an isolated volume between the first and second valve members (20,22;120,122); a monitoring arrangement for obtaining information relating to a condition in the isolated volume ; and a communication arrangement for communicating the information relating to the condition in the isolated volume to a remote location, wherein the communication arrangement is configured to transmit or otherwise relay the information relating to the condition in the isolated volume to the remote location via at least one intermediate location, wherein the at least one intermediate location comprises a first intermediate location located at a subterranean location in the wellbore uphole from the second valve member, the communication arrangement comprising a first receiver/transmitter or transceiver disposed at the first intermediate location, wherein the communication arrangement comprises a wireless communication arrangement configured to transmit or otherwise relay the information relating to the condition in the isolated volume to the first receiver/transmitter or transceiver wirelessly. <EOS>