A web site dicussing the Boston Tea Party has the following paragraph:
Two hundred thirty-nine years later, young John’s find, one of only two known surviving tea chests from the Boston Tea Party, and known now as the Robinson Half Chest, is on display in the Boston Tea Party Ships & Museum in Boston.
Where is the other surviving chest from the Boston Tea Party (Not the Robinson chest)? What is the story of this other chest, and what does it look like?
The Boston Tea Party Ships & Museum reopened in 2012 with the Robinson Tea Chest as one of their main attractions. The site referenced by OP lays out the provenance of the chest, which is largely considered to be an authentic relic of the Boston Tea Party. When the museum opened it was believed that there was a second surviving tea chest and this was reflected in promotional materials and in onsite tour content.
What has been referenced as "the other surviving chest" is a chest at the museum of the Daughters of the American Revolution, which is no longer considered to be a survivor from the Boston Tea Party. It's recently been dated to a few decades after the event. You can see it in their collections.
You can read more about its story in boston1775.blogspot.com
During my time as a supervisor at the Boston Tea Party Ships & Museum (2016–2018) we had correspondence with the DAR museum, wherein they confirmed that the chest in their possession was no longer considered a relic of the Boston Tea Party. We then began training actors to speak of the Robinson Tea Chest as the only surviving tea chest. I can't answer why this page on the website has not yet been updated with this change.
There may have been a second tea chest* (of the oft-cited "342 chests of tea destroyed") purloined by one of the Sons of Liberty during their politically-motivated 'direct action' (aka The Boston Tea Party) but it was likely lost or forgotten (then disposed of by accident).
Note: the 'second tea chest', gifted to DAR in the late 1960's by a descendant of John Hancock (John Hancock Foster), has since been 'dis-authenticated', even as the BTP Historical Society site (www.boston-tea-party.org) makes it seem as though this chest is authentic. DAR has acknowledged that it is a replica (empty, of course).
One curious fact (confirming this possibility of a second chest) is that The East India Company's report to Parliament (following the Destruction of the Tea on Dec. 16, 1773) lists only '340 chests of tea' being destroyed/lost -- not the 342 chests that have been noted in all historical accounts. If the EIC's report was to document their losses for a future insurance claim (or tax payment exemption), one would think they would have reported ALL 342 chests (listed on the original ships' manifests or the EIC's records). So then, if we assume that this two-tea-chest discrepancy is related to the "two remaining tea chests"...one of these (presumably authentic) chests remains at the BTP Museum; the other of the two COULD still exist, somewhere (perhaps in a private collection, like so many stolen Artworks).
Also, let us not forget that there was a fourth ship containing EIC tea, the William, which ran aground on Cape Cod. The tea was 'received' and transported to a tea merchant's Boston warehouse where it was later destroyed (presumably, by members of the SoL). So, while this batch of tea was not a 'participant' in the BTP, it could have been the source of the second chest (or others), and again, possibly stolen by one of the 'tea raiders' in that later act of tea-related vandalism. But the EIC report (noted above) was no doubt written before this final act of tea destruction, as the EIC would surely have included it amongst its losses (but I am not aware of any further 'lost tea' or other merchandise report, viz a viz the William, reported by the EIC at any subsequent time. I could be wrong there).
But my guess is that it was stolen at the time of the BTP (and why not?) and consumed later (as it was likely a chest of a then popular commercial 'bohea' tea -- a mixture of black and oolong tea's -- from Fujian China, via Canton). But now, consider all the ways a single chest could be lost or damaged in 250 years!
