Even the lifeboat was effectively beached - unable to leave its main launch site.
Several traders say they had to close or saw a big reduction in takings during the half-term school holidays last week.
The problem was caused by freak weather with strong winds whipping sand off the award-winning Blue Flag beach and onto the promenade.
Bobby Baldwin, who has run the Snack Shack for seven years, said the sand had led to a significant loss for his business.
He said: “The high winds caused the sand to go everywhere and no-one could get access to my business.
“It has been a killer for my trade. Typically, now everyone has gone home after half-term the weather has got better. But it has resulted in me losing a week’s worth of vital business.
“We rely on this busy time of year. It has been like opening up for a week in the middle of winter, not the summer. I saw this same thing happen around three or four years ago and it has not been that bad since then. I spent many hours clearing up sand to the point where my hands couldn’t dig any further.”
Sally Gray, who owns the Bucket and Spade Café at the opposite end of the promenade, had to close her business for three days.
She said: “I have never seen the wind ‘fly up’ the sand as bad as this since I took over the running of this café three years ago. I had to close on Tuesday, Wednesday and Thursday last week and I have seen a big loss in trade.
“Even now, business has not yet picked up.”
Captain Jack’s Adventure Golf also had to close last week. Sand also piled up in front of the Mablethorpe RNLI building but foruntately, they didn’t have a call out as their main launch site was blocked.
Karen Cartwright, press officer and helmswoman for Mablethorpe RNLI, said: “It was a good job we didn’t have any call outs, as we couldn’t take off from our primary launch site. Luckily, we do have a secondary launch site, so if we had a call, we would have launched further down the prom which does take a minute or two longer.”
Traders said the one positive aspect was a community effort with volunteers coming together to help clear the sand.
East Lindsey District Council’s Neighbourhoods Team were also re-directed to help and called in a mini excavator to remove the big mounds.