The Hardest Sudoku Ever

Here is an unutterably brilliant (and mind-bendingly hard) sudoku by Matyas Martinka. The rules are a little complicated but it is worth studying them!
https://cracking-the-cryptic.web.app/...

RULES: Normal sudoku rules apply. Each cell in the grid should be coloured blue (for water) or green (for land). For cells containing arrows, the digit in that cell shows how many cells share the same colour with the cell in the given direction, NOT including the arrow cell itself. Note that these same-colour cells need not be connected to the arrow cell. Not all arrows are given. The water occupies a single orthogonally connected region of the grid but no 2x2 area can contain only water cells. An island is an orthogonally connected region of at least 3 land cells. All land cells must be part of islands (so land cells are always in groups of three or more orthogonally connected cells). Islands may touch each other diagonally. Land cells forming any island must contain different digits.

Scott Strosahl's Junior Puzzle Hunt is available free here:
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Mitchell Lee's Miracle Sudoku continues to garner amazing feedback. Do check it out here:    • The Miracle Sudoku  

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Hi! We're Simon Anthony and Mark Goodliffe, two of the UK's most enthusiastic puzzle solvers. We have both represented the UK at the World Sudoku Championships and the World Puzzle Championships. We're also "cryptic crossword" aficionados. Mark is the twelve-time winner of The Times championship and Simon is the former record holder for most consecutive correct solutions to The Listener crossword. We hope we can help your puzzle solving while also introducing you to some of the world's best puzzles.

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Simon and Mark