There are a couple of places mentioned in Roger Deakin’s Waterlog that are good for wild swimming ie in the River Waveney at Outney Meadow just on the edge of Bungay and downstream from the Locks Inn at Geldeston. The Big Dog Ferry will take you to Geldeston from Beccles .Join the locals in jumping from the bridge or clamber down the bank and swim amongst the reeds and ducks with lunch or a drink at the pub afterwards
For sea swimming, Covehithe is good (where you can see at first hand the eroding coastline), as is Southwold and Walberswick which has a gently shelving beach of mostly sand with shingle. When the tide’s out at Walberswick there’s a large pool (near the mouth of the river) which small children love to splash in. (The dunes help create a sheltered environment too).
The Blyth Estuary is a great place to visit in any season, following the river as it meanders down towards Walberswick and Southwold; in autumn, you might be lucky enough to see a murmuration of starlings (in an area that’s not short of wildlife) and you will generally hear curlews calling and, when the tide is out, thousands of gulls, waders, oyster catchers, avocets and seabirds on the huge mudflats.
Down by the quay, you can stop at the shacks to buy fish straight off the boats or even treat yourself to an excellent lunch at the Sole Bay Fish Co.
Orford Ness is a wild and mysterious place to explore; it’s accessible only by ferry boat, courtesy of the National Trust. Once you’ve visited the Ness, be sure to take in Pinney’s of Orford’s shop for wonderful seafood.