Luckily it's not all grit, warehouses and landfill sites. Rainham Marshes, the first part of our journey, is beautiful - several miles of paved bike tracks, flowers, drainage ditches and these beautifully appropriate bridges which suit the landscape so well.
Where the path meets the river is a graveyard of old ferro-concrete barges, permanently moored up and in various states of buoyancy.
The RSPB visitor centre at Rainham marshes is an interesting building which has a cafe overlooking the reserve and a large picnic area in the garden below. We didn't have time to get out into the reserve but it has several hides and a load of boardwalks so could be a good place to check out for a future day out.
The 'world's largest yacht' (I always thought yachts were meant to have sails) the MV Octopus passed by as we were at the cafe, leaving London after being berthed there during the Olympics.
In Thurrock a complete surprise awaited us as we came across the Royal Opera House's education and set-building centre at High House Production Park. It was a weird discovery of a little oasis of culture and beauty among grim housing estates and grubby industrial parks.
Further on from the ROH site we headed to St Clements Church, a peculiar sight right next to Proctor & Gamble's chemical works in the middle of a huge industrial estate. A smell like the combination of every pongy cleaning fluid in the world hung in the air, it did not make the place feel clean - quite the opposite in fact. St Clement's is a lovely church in a totally bizarre location; apparently was used as the location for the funeral in Four Weddings and a Funeral (not that I can remember, which won't surprise anyone who knows me and my memory for films :-/).
At Grays we decided to hop on the train for one stop, to avoid having to ride along busy roads with all the articulated lorries and white vans which we'd already had our fill of. Grays is a depressing place. And then we arrived at Tilbury Town and immediately revised our opinion of Grays.
Luckily we weren't in the 'town' very long and were soon heading back to the river en route to Tilbury Fort, one of the country's best preserved forts, originally founded by Henry VIII. Best photographed from the air, as the link shows!
Unfortunately we chose one of the two weekdays when it happened to be closed, but on the plus side, it was a quiet and peaceful time to be there and we pootled around for a while enjoying the views over the river and the power station, and watching the boats go by.
We weren't sure if we could get along the river much further - there's no official cycle route but seemed to be a footpath marked on the map. Luckily we met an old chap on a bike coming the other way who assured us that apart from having to carry our bikes up and down a couple of sets of stairs, we could get right through to Coalhouse Fort, our ultimate destination.
Final stop before the train home was the modernist Bata factory in East Tilbury, specifically requested by Gareth for architectural curiosity. Lots of photos were taken, I'm sure they'll be up on his blog before too long!
A glorious sunset over Tower Bridge and the Shard rounded the trip off beautifully. Despite a long and hot day out, the ride home cooled me down and made for a fitting end.