diff --git a/src/core/enum_type.hpp b/src/core/enum_type.hpp
index cabefee043..533f734825 100644
--- a/src/core/enum_type.hpp
+++ b/src/core/enum_type.hpp
@@ -60,4 +60,19 @@ debug_inline constexpr bool HasFlag(const T x, const T y)
 	return (x & y) == y;
 }
 
+/**
+ * Toggle a value in a bitset enum.
+ * @param x The value to change.
+ * @param y The flag to toggle.
+ */
+template <typename T, class = typename std::enable_if_t<std::is_enum_v<T>>>
+debug_inline constexpr void ToggleFlag(T &x, const T y)
+{
+	if (HasFlag(x, y)) {
+		x &= ~y;
+	} else {
+		x |= y;
+	}
+}
+
 #endif /* ENUM_TYPE_HPP */
diff --git a/src/genworld_gui.cpp b/src/genworld_gui.cpp
index 1ddd0c916c..31caf9cb14 100644
--- a/src/genworld_gui.cpp
+++ b/src/genworld_gui.cpp
@@ -479,11 +479,11 @@ struct GenerateLandscapeWindow : public Window {
 			case WID_GL_RIVER_PULLDOWN:      SetDParam(0, _rivers[_settings_newgame.game_creation.amount_of_rivers]); break;
 			case WID_GL_SMOOTHNESS_PULLDOWN: SetDParam(0, _smoothness[_settings_newgame.game_creation.tgen_smoothness]); break;
 			case WID_GL_VARIETY_PULLDOWN:    SetDParam(0, _variety[_settings_newgame.game_creation.variety]); break;
-			case WID_GL_BORDERS_RANDOM:      SetDParam(0, (_settings_newgame.game_creation.water_borders == BORDERS_RANDOM) ? STR_MAPGEN_BORDER_RANDOMIZE : STR_MAPGEN_BORDER_MANUAL); break;
-			case WID_GL_WATER_NE: SetDParam(0, (_settings_newgame.game_creation.water_borders == BORDERS_RANDOM) ? STR_MAPGEN_BORDER_RANDOM : HasBit(_settings_newgame.game_creation.water_borders, BORDER_NE) ? STR_MAPGEN_BORDER_WATER : STR_MAPGEN_BORDER_FREEFORM); break;
-			case WID_GL_WATER_NW: SetDParam(0, (_settings_newgame.game_creation.water_borders == BORDERS_RANDOM) ? STR_MAPGEN_BORDER_RANDOM : HasBit(_settings_newgame.game_creation.water_borders, BORDER_NW) ? STR_MAPGEN_BORDER_WATER : STR_MAPGEN_BORDER_FREEFORM); break;
-			case WID_GL_WATER_SE: SetDParam(0, (_settings_newgame.game_creation.water_borders == BORDERS_RANDOM) ? STR_MAPGEN_BORDER_RANDOM : HasBit(_settings_newgame.game_creation.water_borders, BORDER_SE) ? STR_MAPGEN_BORDER_WATER : STR_MAPGEN_BORDER_FREEFORM); break;
-			case WID_GL_WATER_SW: SetDParam(0, (_settings_newgame.game_creation.water_borders == BORDERS_RANDOM) ? STR_MAPGEN_BORDER_RANDOM : HasBit(_settings_newgame.game_creation.water_borders, BORDER_SW) ? STR_MAPGEN_BORDER_WATER : STR_MAPGEN_BORDER_FREEFORM); break;
+			case WID_GL_BORDERS_RANDOM:      SetDParam(0, (_settings_newgame.game_creation.water_borders == Borders::Random) ? STR_MAPGEN_BORDER_RANDOMIZE : STR_MAPGEN_BORDER_MANUAL); break;
+			case WID_GL_WATER_NE: SetDParam(0, (_settings_newgame.game_creation.water_borders == Borders::Random) ? STR_MAPGEN_BORDER_RANDOM : HasFlag(_settings_newgame.game_creation.water_borders, Borders::NorthEast) ? STR_MAPGEN_BORDER_WATER : STR_MAPGEN_BORDER_FREEFORM); break;
+			case WID_GL_WATER_NW: SetDParam(0, (_settings_newgame.game_creation.water_borders == Borders::Random) ? STR_MAPGEN_BORDER_RANDOM : HasFlag(_settings_newgame.game_creation.water_borders, Borders::NorthWest) ? STR_MAPGEN_BORDER_WATER : STR_MAPGEN_BORDER_FREEFORM); break;
+			case WID_GL_WATER_SE: SetDParam(0, (_settings_newgame.game_creation.water_borders == Borders::Random) ? STR_MAPGEN_BORDER_RANDOM : HasFlag(_settings_newgame.game_creation.water_borders, Borders::SouthEast) ? STR_MAPGEN_BORDER_WATER : STR_MAPGEN_BORDER_FREEFORM); break;
+			case WID_GL_WATER_SW: SetDParam(0, (_settings_newgame.game_creation.water_borders == Borders::Random) ? STR_MAPGEN_BORDER_RANDOM : HasFlag(_settings_newgame.game_creation.water_borders, Borders::SouthWest) ? STR_MAPGEN_BORDER_WATER : STR_MAPGEN_BORDER_FREEFORM); break;
 			case WID_GL_HEIGHTMAP_ROTATION_PULLDOWN: SetDParam(0, _rotation[_settings_newgame.game_creation.heightmap_rotation]); break;
 
 			case WID_GL_HEIGHTMAP_SIZE_TEXT:
@@ -517,15 +517,15 @@ struct GenerateLandscapeWindow : public Window {
 			this->SetWidgetDisabledState(WID_GL_SMOOTHNESS_PULLDOWN, _settings_newgame.game_creation.land_generator == LG_ORIGINAL);
 			this->SetWidgetDisabledState(WID_GL_VARIETY_PULLDOWN, _settings_newgame.game_creation.land_generator == LG_ORIGINAL);
 			this->SetWidgetDisabledState(WID_GL_BORDERS_RANDOM, _settings_newgame.game_creation.land_generator == LG_ORIGINAL || !_settings_newgame.construction.freeform_edges);
-			this->SetWidgetsDisabledState(_settings_newgame.game_creation.land_generator == LG_ORIGINAL || !_settings_newgame.construction.freeform_edges || _settings_newgame.game_creation.water_borders == BORDERS_RANDOM,
+			this->SetWidgetsDisabledState(_settings_newgame.game_creation.land_generator == LG_ORIGINAL || !_settings_newgame.construction.freeform_edges || _settings_newgame.game_creation.water_borders == Borders::Random,
 					WID_GL_WATER_NW, WID_GL_WATER_NE, WID_GL_WATER_SE, WID_GL_WATER_SW);
 
-			this->SetWidgetLoweredState(WID_GL_BORDERS_RANDOM, _settings_newgame.game_creation.water_borders == BORDERS_RANDOM);
+			this->SetWidgetLoweredState(WID_GL_BORDERS_RANDOM, _settings_newgame.game_creation.water_borders == Borders::Random);
 
-			this->SetWidgetLoweredState(WID_GL_WATER_NW, HasBit(_settings_newgame.game_creation.water_borders, BORDER_NW));
-			this->SetWidgetLoweredState(WID_GL_WATER_NE, HasBit(_settings_newgame.game_creation.water_borders, BORDER_NE));
-			this->SetWidgetLoweredState(WID_GL_WATER_SE, HasBit(_settings_newgame.game_creation.water_borders, BORDER_SE));
-			this->SetWidgetLoweredState(WID_GL_WATER_SW, HasBit(_settings_newgame.game_creation.water_borders, BORDER_SW));
+			this->SetWidgetLoweredState(WID_GL_WATER_NW, HasFlag(_settings_newgame.game_creation.water_borders, Borders::NorthWest));
+			this->SetWidgetLoweredState(WID_GL_WATER_NE, HasFlag(_settings_newgame.game_creation.water_borders, Borders::NorthEast));
+			this->SetWidgetLoweredState(WID_GL_WATER_SE, HasFlag(_settings_newgame.game_creation.water_borders, Borders::SouthEast));
+			this->SetWidgetLoweredState(WID_GL_WATER_SW, HasFlag(_settings_newgame.game_creation.water_borders, Borders::SouthWest));
 
 			this->SetWidgetsDisabledState(_settings_newgame.game_creation.land_generator == LG_ORIGINAL && (_settings_newgame.game_creation.landscape == LT_ARCTIC || _settings_newgame.game_creation.landscape == LT_TROPIC),
 					WID_GL_TERRAIN_PULLDOWN, WID_GL_WATER_PULLDOWN);
@@ -829,27 +829,27 @@ struct GenerateLandscapeWindow : public Window {
 
 			/* Freetype map borders */
 			case WID_GL_WATER_NW:
-				_settings_newgame.game_creation.water_borders = ToggleBit(_settings_newgame.game_creation.water_borders, BORDER_NW);
+				ToggleFlag(_settings_newgame.game_creation.water_borders, Borders::NorthWest);
 				this->InvalidateData();
 				break;
 
 			case WID_GL_WATER_NE:
-				_settings_newgame.game_creation.water_borders = ToggleBit(_settings_newgame.game_creation.water_borders, BORDER_NE);
+				ToggleFlag(_settings_newgame.game_creation.water_borders, Borders::NorthEast);
 				this->InvalidateData();
 				break;
 
 			case WID_GL_WATER_SE:
-				_settings_newgame.game_creation.water_borders = ToggleBit(_settings_newgame.game_creation.water_borders, BORDER_SE);
+				ToggleFlag(_settings_newgame.game_creation.water_borders, Borders::SouthEast);
 				this->InvalidateData();
 				break;
 
 			case WID_GL_WATER_SW:
-				_settings_newgame.game_creation.water_borders = ToggleBit(_settings_newgame.game_creation.water_borders, BORDER_SW);
+				ToggleFlag(_settings_newgame.game_creation.water_borders, Borders::SouthWest);
 				this->InvalidateData();
 				break;
 
 			case WID_GL_BORDERS_RANDOM:
-				_settings_newgame.game_creation.water_borders = (_settings_newgame.game_creation.water_borders == BORDERS_RANDOM) ? 0 : BORDERS_RANDOM;
+				_settings_newgame.game_creation.water_borders = (_settings_newgame.game_creation.water_borders == Borders::Random) ? Borders::None : Borders::Random;
 				this->InvalidateData();
 				break;
 
diff --git a/src/landscape_type.h b/src/landscape_type.h
index 81bed326e2..602d314d61 100644
--- a/src/landscape_type.h
+++ b/src/landscape_type.h
@@ -10,6 +10,7 @@
 #ifndef LANDSCAPE_TYPE_H
 #define LANDSCAPE_TYPE_H
 
+#include "core/enum_type.hpp"
 typedef uint8_t LandscapeID; ///< Landscape type. @see LandscapeType
 
 /** Landscape types */
@@ -25,12 +26,15 @@ enum LandscapeType {
 /**
  * For storing the water borders which shall be retained.
  */
-enum Borders {
-	BORDER_NE = 0,
-	BORDER_SE = 1,
-	BORDER_SW = 2,
-	BORDER_NW = 3,
-	BORDERS_RANDOM = 16,
+enum class Borders : uint8_t {
+	None = 0,
+	NorthEast = 1U << 0, ///< Border on North East.
+	SouthEast = 1U << 1, ///< Border on South East.
+	SouthWest = 1U << 2, ///< Border on South West.
+	NorthWest = 1U << 3, ///< Border on North West.
+	Random = 1U << 4, ///< Randomise borders.
+	All = NorthEast | SouthEast | SouthWest | NorthWest, ///< Border on all sides.
 };
+DECLARE_ENUM_AS_BIT_SET(Borders)
 
 #endif /* LANDSCAPE_TYPE_H */
diff --git a/src/settings_type.h b/src/settings_type.h
index 157bdf6058..b086bc2950 100644
--- a/src/settings_type.h
+++ b/src/settings_type.h
@@ -366,7 +366,7 @@ struct GameCreationSettings {
 	uint8_t se_flat_world_height;             ///< land height a flat world gets in SE
 	uint8_t town_name;                        ///< the town name generator used for town names
 	uint8_t landscape;                        ///< the landscape we're currently in
-	uint8_t water_borders;                    ///< bitset of the borders that are water
+	Borders water_borders;                    ///< bitset of the borders that are water
 	uint16_t custom_town_number;               ///< manually entered number of towns
 	uint16_t custom_industry_number;           ///< manually entered number of industries
 	uint8_t variety;                          ///< variety level applied to TGP
diff --git a/src/tgp.cpp b/src/tgp.cpp
index 1ce32fda86..99f14da30f 100644
--- a/src/tgp.cpp
+++ b/src/tgp.cpp
@@ -718,7 +718,7 @@ static double perlin_coast_noise_2D(const double x, const double y, const double
  * Please note that all the small numbers; 53, 101, 167, etc. are small primes
  * to help give the perlin noise a bit more of a random feel.
  */
-static void HeightMapCoastLines(uint8_t water_borders)
+static void HeightMapCoastLines(Borders water_borders)
 {
 	int smallest_size = std::min(_settings_game.game_creation.map_x, _settings_game.game_creation.map_y);
 	const int margin = 4;
@@ -728,7 +728,7 @@ static void HeightMapCoastLines(uint8_t water_borders)
 
 	/* Lower to sea level */
 	for (y = 0; y <= _height_map.size_y; y++) {
-		if (HasBit(water_borders, BORDER_NE)) {
+		if (HasFlag(water_borders, Borders::NorthEast)) {
 			/* Top right */
 			max_x = abs((perlin_coast_noise_2D(_height_map.size_y - y, y, 0.9, 53) + 0.25) * 5 + (perlin_coast_noise_2D(y, y, 0.35, 179) + 1) * 12);
 			max_x = std::max((smallest_size * smallest_size / 64) + max_x, (smallest_size * smallest_size / 64) + margin - max_x);
@@ -738,7 +738,7 @@ static void HeightMapCoastLines(uint8_t water_borders)
 			}
 		}
 
-		if (HasBit(water_borders, BORDER_SW)) {
+		if (HasFlag(water_borders, Borders::SouthWest)) {
 			/* Bottom left */
 			max_x = abs((perlin_coast_noise_2D(_height_map.size_y - y, y, 0.85, 101) + 0.3) * 6 + (perlin_coast_noise_2D(y, y, 0.45,  67) + 0.75) * 8);
 			max_x = std::max((smallest_size * smallest_size / 64) + max_x, (smallest_size * smallest_size / 64) + margin - max_x);
@@ -751,7 +751,7 @@ static void HeightMapCoastLines(uint8_t water_borders)
 
 	/* Lower to sea level */
 	for (x = 0; x <= _height_map.size_x; x++) {
-		if (HasBit(water_borders, BORDER_NW)) {
+		if (HasFlag(water_borders, Borders::NorthWest)) {
 			/* Top left */
 			max_y = abs((perlin_coast_noise_2D(x, _height_map.size_y / 2, 0.9, 167) + 0.4) * 5 + (perlin_coast_noise_2D(x, _height_map.size_y / 3, 0.4, 211) + 0.7) * 9);
 			max_y = std::max((smallest_size * smallest_size / 64) + max_y, (smallest_size * smallest_size / 64) + margin - max_y);
@@ -761,7 +761,7 @@ static void HeightMapCoastLines(uint8_t water_borders)
 			}
 		}
 
-		if (HasBit(water_borders, BORDER_SE)) {
+		if (HasFlag(water_borders, Borders::SouthEast)) {
 			/* Bottom right */
 			max_y = abs((perlin_coast_noise_2D(x, _height_map.size_y / 3, 0.85, 71) + 0.25) * 6 + (perlin_coast_noise_2D(x, _height_map.size_y / 3, 0.35, 193) + 0.75) * 12);
 			max_y = std::max((smallest_size * smallest_size / 64) + max_y, (smallest_size * smallest_size / 64) + margin - max_y);
@@ -811,18 +811,18 @@ static void HeightMapSmoothCoastInDirection(int org_x, int org_y, int dir_x, int
 }
 
 /** Smooth coasts by modulating height of tiles close to map edges with cosine of distance from edge */
-static void HeightMapSmoothCoasts(uint8_t water_borders)
+static void HeightMapSmoothCoasts(Borders water_borders)
 {
 	int x, y;
 	/* First Smooth NW and SE coasts (y close to 0 and y close to size_y) */
 	for (x = 0; x < _height_map.size_x; x++) {
-		if (HasBit(water_borders, BORDER_NW)) HeightMapSmoothCoastInDirection(x, 0, 0, 1);
-		if (HasBit(water_borders, BORDER_SE)) HeightMapSmoothCoastInDirection(x, _height_map.size_y - 1, 0, -1);
+		if (HasFlag(water_borders, Borders::NorthWest)) HeightMapSmoothCoastInDirection(x, 0, 0, 1);
+		if (HasFlag(water_borders, Borders::SouthEast)) HeightMapSmoothCoastInDirection(x, _height_map.size_y - 1, 0, -1);
 	}
 	/* First Smooth NE and SW coasts (x close to 0 and x close to size_x) */
 	for (y = 0; y < _height_map.size_y; y++) {
-		if (HasBit(water_borders, BORDER_NE)) HeightMapSmoothCoastInDirection(0, y, 1, 0);
-		if (HasBit(water_borders, BORDER_SW)) HeightMapSmoothCoastInDirection(_height_map.size_x - 1, y, -1, 0);
+		if (HasFlag(water_borders, Borders::NorthEast)) HeightMapSmoothCoastInDirection(0, y, 1, 0);
+		if (HasFlag(water_borders, Borders::SouthWest)) HeightMapSmoothCoastInDirection(_height_map.size_x - 1, y, -1, 0);
 	}
 }
 
@@ -865,8 +865,8 @@ static void HeightMapNormalize()
 
 	HeightMapAdjustWaterLevel(water_percent, h_max_new);
 
-	uint8_t water_borders = _settings_game.construction.freeform_edges ? _settings_game.game_creation.water_borders : 0xF;
-	if (water_borders == BORDERS_RANDOM) water_borders = GB(Random(), 0, 4);
+	Borders water_borders = _settings_game.construction.freeform_edges ? _settings_game.game_creation.water_borders : Borders::All;
+	if (water_borders == Borders::Random) water_borders = static_cast<Borders>(GB(Random(), 0, 4));
 
 	HeightMapCoastLines(water_borders);
 	HeightMapSmoothSlopes(roughness);