This puzzle is a combination of a Nurikabe and a 6x6 Chaos Construction Sudoku. The two grids are linked together: the digit in each cell of the Sudoku grid must equal the number of land cells in the corresponding 2x3 box in the Nurikabe grid.
Nurikabe: Every cell is either water or land. All water cells must be orthogonally connected, and no 2x2 area may be entirely water. Clues must be on land cells, and every orthogonally connected area of land cells contains exactly one clue, the value of which represents the size of the area. A “?” can represent any non-zero size.
Sudoku: Divide the grid into regions, each consisting of 6 orthogonally connected cells. Each row, column, and region must contain the digits 1 to 6 once each. A digit in a cell with arrows indicates the number of cells seen in the indicated directions combined, including itself. Region borders obstruct vision.