It was meant to be a recce for her long-distance swim.
But Anna Wardley and her team got stuck in the mud on a falling tide off Hilsea Lines.
The 36-year-old said it highlights the difficulty in plotting a swim through uncharted waters.
Anna, 36, said: ‘Our three-hour recce turned into an adventure.
‘Being stuck on the mud for seven hours on a 4.5-metre RIB with no shelter or toilet facilities provided a great bonding session for my support team, especially as we managed to go aground between the busy motorway and the pathway along Hilsea Lines.’
Luckily, the team was well-prepared with safety equipment, lifejackets and bad weather gear to cope with the chilly conditions.
Anna added: ‘We’d like to thank Solent Coastguard and its Portsmouth mobile unit for responding to a call from a concerned member of the public who spotted us waiting for the tide to come in to float us off.
‘Although we had everything we needed on board, it’s comforting to know that the coastguard is on hand to help should we ever get into difficulties.’
Anna is preparing for a world record swim that will see her swimming around islands in Spain, Jersey, the Isle of Wight and the Isle of Tiree in Scotland, as well as Portsea Island.