Hertfordshire's boundaries are typical of the arbitrary approach to jurisdictions of the late Saxon era. As a consequence, the countrysides, landscapes and urbanisations within Hertfordshire are fairly diverse, each type of countryside with its own distinct characteristics.
In the south, Hertfordshire is mainly metropolitan with scrubby countryside masquerading as green belt (the locals tend to stick horses in these fields, like tourists placing towels over sun chairs). The metropolitan areas range from the "plush" feel of the original Metroland in the west, to the more "functional" feel of suburban sprawl in the east. Hertfordshire boasts two Garden Cities (Letchworth and Welwyn), two New Towns (Stevenage and Hemel Hempstead), one London Overspill (Borehamwood) and one Liberty (St Albans), each of which have a rich tapestry of history to pick through.
In the north, Hertfordshire is mainly rural (especially northern East Herts District). The rural areas are mainly agricultural spaces: wide fields, often monoculture, whose farmers respect public rights of way by maintaining proper paths, gates and tracks. In contrast to farmers in southern Beds and western Essex, Herts' farmers demonstrate an understanding of biodiversity and traditional land management by maintaining a greater proportion of land for "set-aside" (wild flower zones, piles of wood for bug hotels, etc). Since around 2010, we see more circumstantial evidence of reduced herbicides and pesticides, with some fields positively teeming with life during the late spring/early summer months. Since 2018, and particularly since 2020, we see an apparent acceleration in the "re-wilding agenda". Within the creases of the landscape, we find chocolate-box villages in the east and west of Herts, with more functional villages in the middle of Herts.
All areas of Hertfordshire contain nature reserves of some description, with the Herts & Middx Wildlife Trust active in many cases. Local authorities seem to be enthusiastic to have their green spaces - parks - be accredited under the Green Flag scheme. Herts' Rights of Way is particularly keen on its waymarking, which is arguably the most comprehensive and clear waymarking of the northern home counties.
The geology of Hertfordshire is also fairly diverse. The minor ripples of the Chiltern Hills cut across the northern edge of Herts. Much of the Chilterns' Area of Outstanding Natural Beauty sit in Buckinghamshire. The Hills barge their way into Herts at Berkhampstead & Tring, driving north-eastwards towards Luton. This area of West Herts is the most hilly. The Hills continue their drive with more modest bumps in the landscape towards Hitchin, then continue towards Royston. At any point on this range of hills, the views north and north-east are those of looking from on high to open, wide, flat lands. In east, the views north-east are very long, going deep into Cambridgeshire and fenland. From Royston onwards, the Hills become smaller, becoming the West Anglian Heights, mere speed bumps in comparison to their steeper, taller cousins in Bucks.
South of the Chiltern Hills, heading towards London, the landscape ripples in minor peaks and troughs, until the area roughly occupied by the M25. In the east, views towards the south and south-east reveal the whole of the Thames basin, in which London sits. On a clear day, the skyscrapers of Canary Wharf, the Square Mile and the City are visible. The landscape resumes its hilly nature increasingly as it moves southbound, forming the northern edge of the Thames Basin, then falling again down to the Thames river, except for a minor peak at Hampstead Heath.
Carving their way through most of Hertfordshire are the two major tributaries of the Thames. From Luton, flowing eastwards, then southwards, is the River Lee, ending its route in Hertfordshire as the Lea Valley Regional Park, a strip of flatness in otherwise slightly hilly land. From North Mymms (in the mid-south-east of Herts), flowing westbound, is the River Colne, ending its route in Herts as the Colne Valley Regional Park. The northern-most part of Herts - Hitchin - sits in the basin of the Great Ouse, not the Thames. Rivers in the Thames Basin generally, ultimately, flow southbound; rivers in the Great Ouse basin generally, ultimately, flow northbound: it can be disorientating if you navigate by river!
Industry has etched its own marks into the geology of Herts. The Grand Union canal floated its way through western Herts, southbound to London. No sooner had the water in the canal settled, then somebody decided to plonk railways all over the place, immediately putting the canal industry into redundancy. Today, only the main railway lines exist, running in sort-of parallel with the main motorways haring northbound out of London. Many branch lines closed during "Beeching's Axe", of which a good number are converted to public rights of way.
Dotted throughout Herts are pockets of ancient woodland, all too fragmented by agriculture to be self-sustaining. Herts has re-wooded in some areas, a notable contribution being the Woodland Trust's Heartwood Forest at Sandridge, St Albans.
Throughout all of Herts, especially in the south, a growing pressure to build housing ("Prescottshire") has resulted in already narrow strips of green belt being thinned still further. It looks likely that any residual green belt will be no greater than, say, Victoria Park, Tower Hamlets: a relatively small patch of green surrounded by brick and concrete. Over the next few years from 2019, we could expect to see the beginnings of a new conurbation, "St Walbanhemwelhathitchenageworthock Hempstead" (Watford, Hemel Hempstead, St Albans, Welwyn, Hatfield, Stevenage, Hitchin, Letchworth and Baldock).
As a result, Herts has a rich countryside experience for the day-walker.