Our image viewers have been adapted to record what you are currently viewing in the viewer URL. This displays several values as url parameters (that is after the question mark and basic url of the image viewer). The url
https://iiif.durham.ac.uk/index.html?manifest=t2mzw12z575f&canvas=t2tq237j291h
includes values for manifest and canvas and so will always load in Mirador the same digital object (using the manifest value) and display the same "page" from it (using the canvas value). If there is only a manifest value it will display the first page until you move to another page (so digitised material consisting of only a single image often does not include a canvas value)
This means that you can save what you are currently viewing as a browser bookmark or in application like Zotero. This only stores the digitised item and page being viewed - it does not retain the amount that the you have zoomed in to the image or the particular area that you are looking at, but just the whole page.