Naval Fuel Bunker, Portsdown Hill, Hampshire

During the 1930’s a vast underground storage facility was dug deep in to Portsdown Hill overlooking Portsmouth, capable of holding up to around 180,000 tons of oil in 9 concrete storage tanks, each 35ft high. During a few visits to the site, we managed to see the entire place.

Portsdown Hill fuel bunker
Portsdown Hill from the M275, with the T45 test rig on the horizon and Paulsgrove chalk pit underneath

Portsmouth’s naval history is a long & proud one which the residents of the city are constantly reminded of living in the shadow of Portsdown Hill. Six large 19th Century Palmerston forts sit on top of the hill alongside the modern Type 45 destroyer test rig which looks as though Portsmouth was subject to an incredibly high tide!

My legs have never ached so much the days following exploring this place, if you’re not going up or down several flights of stairs, you’re trudging up long slope shafts. Perhaps that says more about my physical fitness? There are four entrances to the fuel bunkers, officially labelled North Compound, Top Entrance, Main Access Tunnel & Access Tunnel. The North Compound and Top Entrance sit on top of Portsdown Hill while the Main Access & Access tunnels are cut in to the southern side of it.

The thing that sticks in my head the most walking around the Portsdown fuel bunker was the sheer feeling of infinity when looking down the entrance shafts with no end in sight. Endless walking and feeling like you’re getting nowhere.

Decommissioned in the 1990’s, Portsdown fuel bunker is still in great condition, although the pump room (the deepest part of the bunker) is quickly becoming an oil-filled swimming pool. Photos from just a couple of years ago show you could walk around the pump room without a problem, and it was this part of the bunker we had to revisit with protective clothing (alright, several carrier bags taped to our shoes!) in order to see it. Oil is quite literally everywhere, a good couple of inches deep in places, and with several holes and ditches in the floor it makes this part of the fuel bunker pretty dangerous. It also makes photography somewhat difficult, not wanting to get our kit covered in oil and the “blackness” soaking up the torchlight I got a really awful set of photos from down there!

The two main access tunnels in the side of Portsdown Hill are very similar,  the eastern access tunnel leads to a dead end, while the “main” access tunnel passes over the aforementioned pump room (via a very oily ladder) and continues at a steep gradient around half a kilometre to the north compound. Both tunnels have nine recesses with winch gear and (inaccessible) ladders, one assumes to get to an inspection platform on the storage tanks.

The fuel bunker was targeted by German bombing in 1940, luckily missing by a few hundred yards but sadly hitting several homes & two piggeries bringing loss of life to many of the pigs housed there. Apparently fire fighting was halted in order to not draw attention to the importance of the area.

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114 responses to “Naval Fuel Bunker, Portsdown Hill, Hampshire”

  1. Baz says:

    Paid a visit last night with the missus. Both South entrances are still very much sealed with the doors welded closed and RSJ’s welded to the doors. The North entrance that people have mentioned is no longer there. This has been demolished and back filled.

    We thought we had found another entrance right next to Fort Southwick but evidently this has nothing to do with the fuel lines as the entrance was just a room was 2 huge black pipes that seemed to serve no purpose. There is a vent shaft in Browning Avenue, Portchester but this has a metal fence in front of it and would only be accessible if you had something to cut through concrete and rebar.

  2. Harry says:

    Where about is it and how do you get in

  3. Tom says:

    Are there any entrances still open?

  4. Mark says:

    Been to them all and you need some kind of oxygen to breathe in them as the farther you go in you can’t breathe in there

  5. Gaz McCulloch says:

    Hi, recently moved to port Solent and have started walking the hill. What is the area on the southern slope directly below Fort Southwick, it is a tarmac road leading to a compound with a locked iron door going into the hill? I find it very interesting up there.
    Many thanks
    Gaz M

    • The Urban Explorer says:

      Hi Gaz,

      You have found one of the entrance tunnels to the fuel bunker. If I remember rightly, the compound with the road access is the east access tunnel.

      Portsdown Hill, Naval Fuel Bunker map

      • Gaz McCulloch says:

        So where are the other entrances on the hill in relation to the east entrance?

        • The Urban Explorer says:

          If you rotate that map 90º and just overlay it, it’ll all become very clear.

          • Gaz McCulloch says:

            Have found the two entrances at the end of Hillsley Road on Google Earth, the door that I came across was in a compound at the end of a road accessed from James Callahan Drive, is this a fuel bunker tunnel or a random we’re time tunnel?

      • Johnnny says:

        Where did you get that ‘map’? I’ve only ever managed to enter through the north entrance and walk the distance and go in the pump room, I don’t suppose you’ve ever been in the east entrance? Be interested to hear! Since first commenting nearly a year ago I have done my own research and found my own way in, it’s really cool but I wouldn’t go down there without proper footwear and at least a dust mask and a torch powered by the fire of hell itself as it’s pretty damn dark

        • The Urban Explorer says:


          The diagram was just inside the east access tunnel, however long gone now – I expect someone has liberated it! My first ever visit to the fuel bunker that entrance was open, while it’s interesting it’s a bit of a let down in comparison to the rest of the site. The photo with “7” painted on the wall is from the east tunnel, from memory the entire tunnel is like this, straight, long & with the occasional alcove for the fuel cells.

      • Gary McCulloch says:

        Been up today, 1 entrance is open. Now located all 4. The ww2 bunker and radio station

  6. Johnny says:

    Went today, it is still accessible via the other entrance and seems like the flooding may have subsided? Didn’t go all the way though so who knows

  7. Sam c says:

    I have been 3 times over the last 3 weeks and I haven’t found an open entrance yet

  8. scott andrews says:

    I know of a entrance that will not be secured yet . Pm me I will send you location

    UPDATED: !!!! Please stop e-mailing me. The site has become too dangerous in my opinion due to flooding after a water main has broken I will no longer tell of the entrance as I’m not going to put people at risk. Hope you all understand !!!!

    • Sam says:

      Scott any chance to can get in touch? Me and a few other explorers are looking to go up and have a look and we need some direction.

    • John Travers says:

      Location please, am very much interested

    • Jasmin Lopez says:

      Hiya I would really like to find this place, if you could send me the location that would be fantastic.

    • Chris says:

      Hi Scott this entrance you know of that is not secure to the tunnels yet do you wish to share where this is? Thanks

      • Scott says:

        Anyone wishing to know entrance I’ll share not a problem but not publicly. Also please be aware this site is actually fairly dangerous once inside please if anyone is going you MUST wear protective clothing and footwear and be cautious.

        UPDATE: !!!! Please stop e-mailing me. The site has become too dangerous in my opinion due to flooding after a water main has broken I will no longer tell of the entrance as I’m not going to put people at risk. Hope you all understand !!!!

        • The Urban Explorer says:

          Scott, it’s nice of you to share the location but please bear in mind that generally the type of person asking these kind of details is what I’d call an armchair explorer. They want a postcode, a coordinate, a pin on a map. Minimal effort exploring. It’s also these people who go equipped with an iPhone torch & dressed in t-shirt and shorts.

          The Naval Fuel Bunker is not a hard place to find. There’s plenty of information online. And even if people can’t be bothered to search for that, a good old fashioned walk on Portsdown Hill will uncover this “mystery” in no time at all. Explore!

          In other words, you did the “hard work” in locating your entrance, and it’ll be the lazy explorer that gets it sealed up!

          • just some random guy says:

            Dear The Urban Explorer,

            Sharing ideas and thoughts will always lead us to progress. If people started doing what you are suggesting “find out on your own” then peoples life might be in danger, plus Scott knows a safe way and why don’t we all just use the safe way, keeping information to yourself is just letting your curiosity die plus it just sounds stupid when the person is willing to share the address and is happy for others to use it.

    • Tommy W says:

      Message me the location please bud been searching for this place for nearly a week 😂

    • Sam Rahman says:

      Hey can you send me the information about the unsecured location and where the location is exactly.
      My email is

    • Bleu says:

      Hi I’m on my way and need to know how to get there

    • warren says:

      Hello Scott

      I would love to see this fuel bunker it has been on my list for a while now I know one entrance got sealed please email the entrance

    • SammyG says: I’d like to know of the location if it’s still open :)

    • Mac says:

      Want to go there today could someone send me an unsealed location? Thank you

    • James Adams says:

      Where abouts is the site and where is the entrance I’d love to check it out.

  9. Dan says:

    Unfortunately all entrances have been welded shut with a big steel bar. We went down last Sunday and no way in. :/

    • Paul says:

      Did you only try the 2 fronts or did you try one of the other 2?

      • Jonesy says:

        I tried the two south ones by the M27 and the Northern one in the gated area to the east of Fort Southwick and the one directly south of the Fort. All are sealed.

      • Dan says:

        I went to the top left one on top of hill. And went to the two big doors by tunnels. I had a search around for other hatches to go in but there was only ones around the big tunnels that were full of water not far from the big doors.

        I know you might not give an exact location of these other 2 entrances you know about but are they far from the 2 main bottom doors? and what ish direction? would be slightly helpful. if wanna email me instead. I would appreciate any direction with it. Thanks

  10. Todderic Pritchard says:

    Is there any more entrances any one has found?

  11. Sabercorn 1966 says:

    Went to site last Tuesday 24-10-17, all four entrances still sealed

  12. Jordan says:

    Entrance is now fully sealed up with concrete and a steel beams unfortunately

  13. Danny Kelly says:

    Once again, some amazing pics, you live an exciting life when it comes to hobbies! Keep them coming – Thanks

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