Apart from "Shree VenkataChala-Mahatmya" (about Bhagavan Shree BalaJi also known as Shree VenkatEshwara) "Shree Skanda-Purana" also contains "Shree Purushottama-Kshetra-Mahatmya" (about Bhagavan Shree Jagannatha) with......"out of the blue" plot twist telling about the vision of ShwetaDvipa!
Actually, it is a kind of hidden Chapter in "Shree Skanda-Purana".
"Shree Padma-Purana" and "Shree Skanda-Purana" have a lot of hidden chapters of this kind, that's why an explorer of these brilliant Puranas is similar to a treasure hunter who suddenly reveals very Siddhantic gems!
The chapter about ShwetaDvipa is interesting not only due to ShwetaDvipa itself, but also because of very Siddhantic references to the rules from Vaishnava-Agamas and Vaishnava-Vedanta (see Verses 132-139 below).
The Siddhanta is the following:
1. All the dreams are granted to us by Bhagavan Shree Vishnu (this is Siddhanta from "Shree Vedanta-Sutra", 3.2.1 and further).
2. You should never