I came across this description of Plum Island while searching Google Books for public domain literature about the island.
"But perhaps one of the most recreative in every sense of the word—of the hundreds of gems which geographers have styled islands and which dot the waters of New England's seaboard, is Plum Island. This island is connected with the mainland at Newburyport. so that in reality it is not an island at all, simply a peninsula. The atmosphere is particularly healthful, cool and invigorating, and is guaranteed to soothe the weary and send to slumber the nervous and careworn. Two hotels care for the guests, besides numerous cottages, and it is reached by ferry from Black Rock and electric cars from Newburyport. The electric car line circles the island."
-- The Summer Vacation: Descriptive of the Shore Resorts of New England,
New England Magazine,
"Tending to recreate or refresh; recreating; giving new vigor or animation; reinvigorating; giving relief after labor or pain; amusing; diverting."It is indeed all of those things.
Another interesting thing is that the writer considers it a peninsula connected to the mainland at Newburyport. As far as I know the northern tip of Plum Island (the Newburyport part) was not connected to the mainland. Nowadays the island is connected to the mainland by a bridge, built, as near as I can tell, in 1973. However, according to state and local records a bridge was built over the Plum Island River in 1807 in Newbury. See the History of Plum Island on the Newbury 375th web site. A good 45 minutes of research failed to reveal what happened to the bridge between 1807 and 1973, but I'm pretty sure the bridge was in the same place as it is now when I went there in the 1950s.
The electric trolleys referred to accessed the island from the Plum Island Turnpike over the bridge. MVRTA buses have replaced the trolleys and there is currently no ferry.
If there was another connection to the mainland on the Newburyport end, it will take me a little more research to find it. I guess a 1906 map would help.
As for the hotels, there is currently only one hotel on the island. The hotel was "discovered" by Travel & Leisure magazine last year.