The exact location of hellfire is known by God only although it was described thoroughly in the Quran and Hadith of prophet Mohamed peace be upon him. Some of the descriptions are in the following:

Al-Hasan said:
"While he was on the pulpit – the pulpit of Al-Basrah – `Utbah bin Ghazwain narrated that the Messenger of Allah (s.a.w) said: “Indeed a giant rock can be thrown from the brink of Hell and it will continue to fall into it for seventy years without reaching the bottom of it.”.He said: “`Umar used to say:'Increase in your remembrance of the Fire, for its heat is extreme, its bottom is distant, and its whips are of Iron.'” (Sahih)

حَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، حَدَّثَنَا حُسَيْنُ بْنُ عَلِيٍّ الْجُعْفِيُّ، عَنْ فُضَيْلِ بْنِ عِيَاضٍ، عَنْ هِشَامٍ، عَنِ الْحَسَنِ، قَالَ قَالَ عُتْبَةُ بْنُ غَزْوَانَ عَلَى مِنْبَرِنَا هَذَا مِنْبَرِ الْبَصْرَةِ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ إِنَّ الصَّخْرَةَ الْعَظِيمَةَ لَتُلْقَى مِنْ شَفِيرِ جَهَنَّمَ فَتَهْوِي فِيهَا سَبْعِينَ عَامًا وَمَا تُفْضِي إِلَى قَرَارِهَا ‏"‏ ‏.‏ قَالَ وَكَانَ عُمَرُ يَقُولُ أَكْثِرُوا ذِكْرَ النَّارِ فَإِنَّ حَرَّهَا شَدِيدٌ وَإِنَّ قَعْرَهَا بَعِيدٌ وَإِنَّ مَقَامِعَهَا حَدِيدٌ ‏.‏ قَالَ أَبُو عِيسَى لاَ نَعْرِفُ لِلْحَسَنِ سَمَاعًا مِنْ عُتْبَةَ بْنِ غَزْوَانَ وَإِنَّمَا قَدِمَ عُتْبَةُ بْنُ غَزْوَانَ الْبَصْرَةَ فِي زَمَنِ عُمَرَ وَوُلِدَ الْحَسَنُ لِسَنَتَيْنِ بَقِيَتَا مِنْ خِلاَفَةِ عُمَرَ ‏.‏


In the Quran communications between the people hellfire and Paradise are mentioned (that might suggest that paradise and hellfire are close to each other although parameters are different in the Hereafter).

7:50 Al-A'raaf

‎وَنَادَىٰ أَصْحَابُ النَّارِ أَصْحَابَ الْجَنَّةِ أَنْ أَفِيضُوا عَلَيْنَا مِنَ الْمَاءِ أَوْ مِمَّا رَزَقَكُمُ اللَّهُ ۚ قَالُوا إِنَّ اللَّهَ حَرَّمَهُمَا عَلَى الْكَافِرِينَ

And the dwellers of the Fire will call to the dwellers of Paradise: "Pour on us some water or anything that Allah has provided you with." They will say: "Both (water and provision) Allah has forbidden to the disbelievers." 

 https://media.tenor.com/J_fLDxHnwZEAAAAM/the-dude-lebowski.gif  

 In other words, I don’t know where hellfire is, God knows. 

 i've heard it suggested that the caldera of Tenerife in the Canary Islands was one place, at least, the one the greeks called Tartarus (occurs repeatedly in the new testament translated as hell) and no coincidence that there is a body of water separating it from the rest of the world, or that dogs feature prominently - the hounds of hell, Hades, the name Canary Islands refers to the dogs that are still popular and common all over the atlantic islands 

 So it’s great dogs of fire? Not great balls of fire? 

 haha, nah the dogs and the styx and Charon are in the story because Tartarus was a volcano on an island where people kept dogs

lots of very interesting stuff about these islands too... they get mentions in several ancient greek texts, i think specifically this one, Madeira, and nearby porto santo are known as the "blessed isles" because of their perfect weather... the official portuguese government story is that there is only 600 years of history of humans living here (and on the canaries, cape verde, and the azores) but there is PYRAMIDS on the canaries, and so many signs of ancient human activity everywhere here, 600 years, sure, that stuff is really obvious (all the terracing that has almost completely overgrown and is long out of use) but there is older signs of land being flattened out here and there and old tracks and gouged out stone

yeah, reminds me, i hope i get myself nice and fit by the end of the year i want to climb around randomly in the higher mountain areas in the centre of the island, go right off the track with a scythe in the bag to cut through the odd bit of difficult scrub and see what i see, i know there is caves and all sorts that a lot of it may not have been seen in hundreds if not thousands of years, would be fun, anyway, just to really get lost up there, not like it's hard to find the way out 

 Sounds fun! I’d love to visit as well