Three Heavens

On the first day, God created "the heaven (singular) and the earth" (Genesis 1:1). That's one heaven.

On the second day, God made a firmament and called the firmament "heaven" (Genesis 1:7,8). That's a second heaven.

"Thus the heavens (plural) and the earth were finished..." (Genesis 2:1).

Then Paul mentions a third heaven:

"...such an one caught up to the third heaven" (II Cor.12:2).

Paul also mentions that God hath blessed us with all spiritual blessings "in heavenly places" in Christ (Eph.1:3); and hath raised us up together, and made us sit together "in heavenly places" in Christ Jesus (Eph.2:6); and Paul mentions that we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness "in high places". I'm not sure which heaven is referred to in such passages.