I would be looking at Burghead to Findhorn, or culbin sands for a day trip.
Burghead to Findhorn is a good option at low tide for a good beach run to Finhorn, fill up on Coffee/cake, then you have the option to return via the dunes & forest. Can make a day out of it if the pace is easy going.
Lossiemouth would make a good base for the day, then take East beach in morning & West beach in afternoon.
Culbin is worth going if you take a days supplies with you, as there is nowt there. Work your way through the forest until you drop onto the beach & flats, then ride till the sun sets! Really needs to be planned around low tide, as the is some fantastic riding, but some parts do get cut off when the tide comes in (quickly) which results in a long detour along the sand bar.
It is a great place & well worth a visit 8)
Burghead to Findhorn at high tide
Culbin
From last year’s Lossie to culbin bivi trip…