Today's (15/4/18) Harbour Wallbanger at Broadstairs - a 7.1k beach run in which the going varied from firm wet sand to soft and loose sand to ankle-straining chalk and flint beds, but in the main was a challenging sand run.
If you like something a bit different and are happy to leave the tarmac behind this is a great little race, with the number of runners limited to about 250.