Forbidden Island, released by Liberty in 1958, was Martin Denny's third album, following the success of Exotica and Exotica, Vol. 2, both released the previous year.
Forbidden Island was also Denny's first album recorded without vibraphonist Arthur Lyman, who had left to form a group very similar to Denny's. To replace Lyman, Denny hired Julius Wechter (who would later lead the Baja Marimba Band). But the music didn't change -- a mixture of exotic-sounding instrumentation, easy listening and rain forest sound effects, including lots of bird calls.
Forbidden Island included a couple of Rodgers and Hammerstein songs, March of the Siamese Children from The King and I and Bali Ha'i from South Pacific.
Forbidden Island has received at least two CD reissues -- in 1996 on Scamp when it was paired with Denny's followup, Primateva, and 10 years later by a British label, Rev-Ola. The latter disc included both mono and stereo versions of the album. The Scamp release is top quality but I'm not sure what source was used by Rev-Ola. Both versions are still available online, but are expensive. Forbidden Island also is available as a download from most of the major sources.
From YouTube, here's the title song from Forbidden Island.