SiltFunnelMaelstrom

Portrait endless ring-riding. A band of comparatively safe water circles the funnel: the wall outside it keeps closing inward while the silt core at the centre keeps swelling out, and wherever the finger rests is where the swimmer goes - both the angle and the radius come straight from where you put it. Rubble rides the current around the ring and every chunk that catches you costs a plate of hull, while sand crystals drift in the same band and are yours if you can reach them. The band narrows, the rubble turns faster and comes thicker, and in the end the ring is squeezed too tight for anyone to stand in. A Silt Shield means nothing can bite for six seconds, and a Slow Whirl all but stops the funnel closing for six more. Endless mode with no fixed stage.