Where Are Paradise and Hell?
Question

Where are Paradise and Hell located? Some people say that Hell is in the interior of the earth. Is that true?
Praise be to Allah.Where is Paradise?
What has been stated by the scholars is that Paradise is in the seventh heaven and Hell is in the lowest level of the earth. 
Al-Bukhari (7432) narrated from Abu Hurayrah that the Prophet (blessings and peace of Allah be upon him) said: “If you ask of Allah, then ask Him for al-Firdaws , for it is the middle of Paradise and the highest part of Paradise, and above it is the Throne of the Most Gracious.” 
Al-Bayhaqi narrated in al-Ba‘th wa’n-Nushur (455), with a weak chain of transmission from Ibn Mas‘ud that he said: 
“Paradise is in the seventh, highest heaven and Hell is in the seventh, lowest earth. Then he recited the verses (interpretation of the meaning): “Nay! Verily, the Record (writing of the deeds) of Al-Abrar (the pious who fear Allah and avoid evil), is (preserved) in ‘Illiyyin” [al-Mutaffifin 83:18] and “Nay! Truly, the Record (writing of the deeds) of the Fujjar (disbelievers, sinners, evil-doers and wicked) is (preserved) in Sijjin” [al-Mutaffifin 83:7]. Al-Bayhaqi said immediately after that: The hadith of al-Bara ibn ‘Azib and Abu Hurayrah about the punishment of the grave, and what they narrated from the Prophet (blessings and peace of Allah be upon him) about the location of the soul of the believer and of the disbeliever are indicative of that.”
Al-Hakim (8698) narrated from ‘Abdullah ibn Salam that Paradise is in the heaven and Hell is in the earth. (Classed as sahih by al-Hakim, and adh-Dhahabi agreed with him.)
Al-Hafiz Ibn Rajab (may Allah have mercy on him) said: 
“‘Atiyyah narrated from Ibn 'Abbas, who said: Paradise is in the seventh heaven and Hell is in the seventh earth. This was narrated by Abu Nu‘aym. 
Ibn Mandah narrated from the hadith of Abu Yahya al-Qattat from Mujahid, who said: I said to Ibn 'Abbas: Where is Paradise? He said: Above seven heavens. I said: Where is Hell? He said: Beneath seven seas, one above the other. 
Ibn Abi’d-Dunya narrated with his isnad from Qatadah who said: They used to say that Paradise was in the seventh heaven and that Hell was in the seventh earth. 
Some of them quoted as evidence for that the fact that Allah, may He be exalted, told us that the disbelievers will be shown to the Fire morning and evening, i.e., during the barzakh period [between death and the resurrection] and He told us that no gates of heaven will be opened to them. This indicates that Hell is in the earth.” (At-Takhwif min an-Nar, p. 62-63) 
Ibn ‘Uthaymin (may Allah have mercy on him) was asked: Where are Paradise and Hell? 
He replied: 
“Paradise is in the highest of ‘Illiyyin and Hell is in as-Sijjin, and as-Sijjeen is in the lowest earth, as it says in the hadith: “When the person is dying, Allah, may He be exalted, says: ‘Record the book of My slave in Sijjin in the lowest earth.’” As for Paradise, it is above, in the highest of ‘Illiyyin. It is proven from the Prophet (blessings and peace of Allah be upon him) that “The Throne of the Lord, may He be glorified and exalted, is the roof of Jannat al-Firdaws.” (Fatawa Nur ‘ala ad-Darb, 4/2) 
Where is Hell?
The shaykh also said: 
“The location of Hell is in the earth, but some of the scholars said that it is the oceans, and others said that it is in the centre of the earth. What appears to be the case is that it is in the earth, but we do not know exactly where it is in the earth. 
The evidence that Hell is in the earth is the verse in which Allah, may He be exalted, says: (interpretation of the meaning): “Nay! Truly, the Record (writing of the deeds) of the Fujjar (disbelievers, sinners, evil-doers and wicked) is (preserved) in Sijjin” [al-Mutaffifin 83:7]. Sijjin is the lowest earth, and Hell is in the earth. 
There are hadiths that have been narrated concerning this, but they are da‘if (weak). There are also reports from the early generations, such as Ibn 'Abbas and Ibn Mas‘ud, and this is the apparent meaning of the Quran. Allah, may He be exalted, says (interpretation of the meaning): “Verily, those who belie Our Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.) and treat them with arrogance, for them the gates of heaven will not be opened, and they will not enter Paradise until the camel goes through the eye of the needle (which is impossible)” [al-A‘raf 7:40]. Those who disbelieve in the signs of Allah and are too arrogant to believe in them will undoubtedly be in Hell.” (Ash-Sharh al-Mumti‘, 3/174-175) 
For more, please see this category: Paradise and Hell
And Allah knows best.