Land and Sea
Draw a single, non-intersecting loop that passes orthogonally through all cells. The loop must not go through 3 or more white cells consecutively.
(Example from WPC 2018 IB)
History of the puzzle
Invented by Naoki Inaba (Japan) in 2006.  The name is a literal translation of the original "海と陸".
Appearances in the past WPCs
- WPC 2018/Round 7 by Jan Zvěřina