The seven islands are mentioned in the Siddhanta-siromani: The seven islands (dvipas) are known as (1) Jambu, (2) Saka, (3) Salmali, (4) Kusa, (5) Kraunca, (6) Gomeda, or Plaksa, and (7) Puskara. The planets are called dvipas

Expressions researched:
"The seven islands are mentioned in the Siddhānta-śiromaṇi" |"The seven islands (dvīpas) are known as (1) Jambu, (2) Śāka, (3) Śālmalī, (4) Kuśa, (5) Krauñca, (6) Gomeda, or Plakṣa, and (7) Puṣkara. The planets are called dvīpas"

Sri Caitanya-caritamrta

CC Madhya-lila

The seven islands are mentioned in the Siddhānta-śiromaṇi: The seven islands (dvīpas) are known as (1) Jambu, (2) Śāka, (3) Śālmalī, (4) Kuśa, (5) Krauñca, (6) Gomeda, or Plakṣa, and (7) Puṣkara. The planets are called dvīpas. Outer space is like an ocean of air.

CC Madhya 20.218, Translation and Purport

“Within the universe the Lord is situated in different spiritual manifestations. These are situated on seven islands in nine sections. Thus Their pastimes are going on.

The seven islands are mentioned in the Siddhānta-śiromaṇi:

bhūmer ardhaṁ kṣāra-sindhor udak-sthaṁ

jambu-dvīpaṁ prāhur ācārya-varyāḥ

ardhe ’nyasmin dvīpa-ṣaṭkasya yāmye

kṣāra-kṣīrādy-ambudhīnāṁ niveśaḥ

śākaṁ tataḥ śālmalam atra kauśaṁ

krauñcaṁ ca gomedaka-puṣkare ca

dvayor dvayor antaram ekam ekaṁ

samudrayor dvīpam udāharanti

The seven islands (dvīpas) are known as (1) Jambu, (2) Śāka, (3) Śālmalī, (4) Kuśa, (5) Krauñca, (6) Gomeda, or Plakṣa, and (7) Puṣkara. The planets are called dvīpas. Outer space is like an ocean of air. Just as there are islands in the watery ocean, these planets in the ocean of space are called dvīpas, or islands in outer space. There are nine khaṇḍas, known as (1) Bhārata, (2) Kinnara, (3) Hari, (4) Kuru, (5) Hiraṇmaya, (6) Ramyaka, (7) Ilāvṛta, (8) Bhadrāśva and (9) Ketumāla. These are different parts of Jambudvīpa. A valley between two mountains is called a khaṇḍa or varṣa.