How can I find out if my Great Grandmother was on an immigration ship in 1887 and buried at sea?OLIVE TREE ANSWER: Dear Maureen - there are two parts to your question. First, to find out if your great grandmother was on board a ship in 1887, you must consult the ships' passenger list.
You didn't say where the ship was sailing to so I can't give you specific help, but Ancestry.com has many of the ships passenger lists to USA and Canada indexed and online. You might also check Ships Passenger Lists on Olive Tree Genealogy.
Deaths at sea were recorded on the passenger manifest. So again you need to find the ships' passenger list. You may find the death notation beside the passenger name or you may find it listed on the last page of the manifest.
Whether or not the individual was buried at sea will depend on where the ship was at the time of death. For example my great-great grandmother Sarah (Elvery) Stead died on board ship en route from England to Australia in 1867.
However the ship was either in or very near Sydney Harbour at the time of her death, so Sarah was buried in a cemetery in Sydney. Had they been in the middle of the ocean, I suspect she'd have been buried at sea.