diff --git a/README.md b/README.md
index 2ae7ead8..646b8743 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@
 | ---| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
 | python3 | [✓](src/main/python/AoC2023_01.py) | [✓](src/main/python/AoC2023_02.py) | [✓](src/main/python/AoC2023_03.py) | [✓](src/main/python/AoC2023_04.py) | [✓](src/main/python/AoC2023_05.py) | [✓](src/main/python/AoC2023_06.py) | [✓](src/main/python/AoC2023_07.py) | [✓](src/main/python/AoC2023_08.py) | [✓](src/main/python/AoC2023_09.py) | [✓](src/main/python/AoC2023_10.py) | [✓](src/main/python/AoC2023_11.py) | [✓](src/main/python/AoC2023_12.py) | [✓](src/main/python/AoC2023_13.py) | [✓](src/main/python/AoC2023_14.py) | [✓](src/main/python/AoC2023_15.py) | [✓](src/main/python/AoC2023_16.py) | [✓](src/main/python/AoC2023_17.py) | [✓](src/main/python/AoC2023_18.py) | [✓](src/main/python/AoC2023_19.py) | [✓](src/main/python/AoC2023_20.py) | [✓](src/main/python/AoC2023_21.py) |  | [✓](src/main/python/AoC2023_23.py) |  |  |
 | java | [✓](src/main/java/AoC2023_01.java) | [✓](src/main/java/AoC2023_02.java) | [✓](src/main/java/AoC2023_03.java) | [✓](src/main/java/AoC2023_04.java) | [✓](src/main/java/AoC2023_05.java) | [✓](src/main/java/AoC2023_06.java) | [✓](src/main/java/AoC2023_07.java) | [✓](src/main/java/AoC2023_08.java) | [✓](src/main/java/AoC2023_09.java) | [✓](src/main/java/AoC2023_10.java) | [✓](src/main/java/AoC2023_11.java) | [✓](src/main/java/AoC2023_12.java) | [✓](src/main/java/AoC2023_13.java) | [✓](src/main/java/AoC2023_14.java) | [✓](src/main/java/AoC2023_15.java) | [✓](src/main/java/AoC2023_16.java) | [✓](src/main/java/AoC2023_17.java) | [✓](src/main/java/AoC2023_18.java) |  | [✓](src/main/java/AoC2023_20.java) |  | [✓](src/main/java/AoC2023_22.java) | [✓](src/main/java/AoC2023_23.java) |  |  |
-| rust | [✓](src/main/rust/AoC2023_01/src/main.rs) | [✓](src/main/rust/AoC2023_02/src/main.rs) | [✓](src/main/rust/AoC2023_03/src/main.rs) | [✓](src/main/rust/AoC2023_04/src/main.rs) |  | [✓](src/main/rust/AoC2023_06/src/main.rs) | [✓](src/main/rust/AoC2023_07/src/main.rs) | [✓](src/main/rust/AoC2023_08/src/main.rs) | [✓](src/main/rust/AoC2023_09/src/main.rs) |  |  |  |  |  | [✓](src/main/rust/AoC2023_15/src/main.rs) | [✓](src/main/rust/AoC2023_16/src/main.rs) | [✓](src/main/rust/AoC2023_17/src/main.rs) | [✓](src/main/rust/AoC2023_18/src/main.rs) |  |  | [✓](src/main/rust/AoC2023_21/src/main.rs) |  |  |  |  |
+| rust | [✓](src/main/rust/AoC2023_01/src/main.rs) | [✓](src/main/rust/AoC2023_02/src/main.rs) | [✓](src/main/rust/AoC2023_03/src/main.rs) | [✓](src/main/rust/AoC2023_04/src/main.rs) |  | [✓](src/main/rust/AoC2023_06/src/main.rs) | [✓](src/main/rust/AoC2023_07/src/main.rs) | [✓](src/main/rust/AoC2023_08/src/main.rs) | [✓](src/main/rust/AoC2023_09/src/main.rs) |  |  |  |  |  | [✓](src/main/rust/AoC2023_15/src/main.rs) | [✓](src/main/rust/AoC2023_16/src/main.rs) | [✓](src/main/rust/AoC2023_17/src/main.rs) | [✓](src/main/rust/AoC2023_18/src/main.rs) |  |  | [✓](src/main/rust/AoC2023_21/src/main.rs) |  | [✓](src/main/rust/AoC2023_23/src/main.rs) |  |  |
 <!-- @END:ImplementationsTable:2023@ -->
 
 ## 2022
diff --git a/src/main/rust/AoC2023_23/Cargo.toml b/src/main/rust/AoC2023_23/Cargo.toml
new file mode 100644
index 00000000..a4a425f8
--- /dev/null
+++ b/src/main/rust/AoC2023_23/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "AoC2023_23"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+aoc = { path = "../aoc" }
diff --git a/src/main/rust/AoC2023_23/src/main.rs b/src/main/rust/AoC2023_23/src/main.rs
new file mode 100644
index 00000000..102f86ca
--- /dev/null
+++ b/src/main/rust/AoC2023_23/src/main.rs
@@ -0,0 +1,259 @@
+#![allow(non_snake_case)]
+
+use std::{
+    collections::{HashMap, HashSet, VecDeque},
+    str::FromStr,
+};
+
+use aoc::{
+    geometry::Direction,
+    grid::{Cell, CharGrid, Grid},
+    Puzzle,
+};
+
+#[derive(Debug, Eq, Hash, PartialEq)]
+struct Edge {
+    cell: Cell,
+    distance: usize,
+}
+
+struct PathFinder<'a> {
+    grid: &'a CharGrid,
+    start: Cell,
+    end: Cell,
+}
+
+impl<'a> PathFinder<'a> {
+    fn new(grid: &'a CharGrid) -> Self {
+        Self {
+            grid,
+            start: Cell::at(0, 1),
+            end: Cell::at(grid.height() - 1, grid.width() - 2),
+        }
+    }
+
+    fn find_forks(&self) -> HashSet<Cell> {
+        let is_fork = |cell: &Cell| {
+            cell == &self.start
+                || cell == &self.end
+                || self.grid.get(cell) != '#'
+                    && self
+                        .grid
+                        .capital_neighbours(cell)
+                        .iter()
+                        .filter(|n| self.grid.get(n) != '#')
+                        .count()
+                        > 2
+        };
+
+        self.grid.cells().filter(is_fork).collect::<HashSet<Cell>>()
+    }
+
+    fn build_graph(
+        &self,
+        forks: &HashSet<Cell>,
+        downward_slopes_only: bool,
+    ) -> HashMap<Cell, HashSet<Edge>> {
+        let mut graph = HashMap::<Cell, HashSet<Edge>>::new();
+        for fork in forks {
+            let mut q = VecDeque::<(Cell, usize)>::new();
+            q.push_back((*fork, 0_usize));
+            let mut seen = HashSet::<Cell>::new();
+            seen.insert(*fork);
+            while !q.is_empty() {
+                let (cell, distance) = q.pop_front().unwrap();
+                if forks.contains(&cell) && cell != *fork {
+                    graph
+                        .entry(*fork)
+                        .and_modify(|edges| {
+                            edges.insert(Edge { cell, distance });
+                        })
+                        .or_insert(
+                            vec![Edge { cell, distance }]
+                                .into_iter()
+                                .collect::<HashSet<Edge>>(),
+                        );
+                    continue;
+                }
+                for d in Direction::capital() {
+                    let n = match cell.try_at(d) {
+                        Some(val) => val,
+                        None => continue,
+                    };
+                    if !self.grid.in_bounds(&n) {
+                        continue;
+                    }
+                    let val = self.grid.get(&n);
+                    if val == '#'
+                        || (downward_slopes_only
+                            && ['v', '^', '<', '>'].contains(&val)
+                            && Direction::from_str(&val.to_string()).unwrap()
+                                != d)
+                    {
+                        continue;
+                    }
+                    if !seen.contains(&n) {
+                        seen.insert(n);
+                        q.push_back((n, distance + 1));
+                    }
+                }
+            }
+        }
+        graph
+    }
+
+    fn find_longest(
+        graph: &HashMap<Cell, HashSet<Edge>>,
+        curr: Cell,
+        end: &Cell,
+        seen: &mut HashSet<Cell>,
+    ) -> i32 {
+        if curr == *end {
+            return 0;
+        }
+        let mut ans: i32 = -1_000_000_000;
+        seen.insert(curr);
+        for Edge { cell, distance } in graph.get(&curr).unwrap().iter() {
+            if seen.contains(cell) {
+                continue;
+            }
+            ans = ans.max(
+                *distance as i32 + Self::find_longest(graph, *cell, end, seen),
+            );
+        }
+        seen.remove(&curr);
+        ans
+    }
+
+    fn find_longest_hike_length_with_only_downward_slopes(&self) -> u32 {
+        let forks = self.find_forks();
+        let graph = self.build_graph(&forks, true);
+        Self::find_longest(
+            &graph,
+            self.start,
+            &self.end,
+            &mut HashSet::<Cell>::new(),
+        ) as u32
+    }
+
+    fn find_longest_hike_length(&self) -> u32 {
+        let forks = self.find_forks();
+        let graph = self.build_graph(&forks, false);
+        let dist_from_start = graph
+            .get(&self.start)
+            .unwrap()
+            .iter()
+            .nth(0)
+            .unwrap()
+            .distance;
+        let dist_to_end = graph
+            .get(&self.end)
+            .unwrap()
+            .iter()
+            .nth(0)
+            .unwrap()
+            .distance;
+        let new_start = graph
+            .iter()
+            .filter(|(_, edges)| {
+                edges.contains(&Edge {
+                    cell: self.start,
+                    distance: dist_from_start,
+                })
+            })
+            .map(|(cell, _)| cell)
+            .nth(0)
+            .unwrap();
+        let new_end = graph
+            .iter()
+            .filter(|(_, edges)| {
+                edges.contains(&Edge {
+                    cell: self.end,
+                    distance: dist_to_end,
+                })
+            })
+            .map(|(cell, _)| cell)
+            .nth(0)
+            .unwrap();
+        dist_from_start as u32
+            + dist_to_end as u32
+            + Self::find_longest(
+                &graph,
+                *new_start,
+                new_end,
+                &mut HashSet::<Cell>::new(),
+            ) as u32
+    }
+}
+
+struct AoC2023_23;
+
+impl AoC2023_23 {}
+
+impl aoc::Puzzle for AoC2023_23 {
+    type Input = CharGrid;
+    type Output1 = u32;
+    type Output2 = u32;
+
+    aoc::puzzle_year_day!(2023, 23);
+
+    fn parse_input(&self, lines: Vec<String>) -> CharGrid {
+        CharGrid::from(&lines.iter().map(AsRef::as_ref).collect())
+    }
+
+    fn part_1(&self, grid: &CharGrid) -> u32 {
+        PathFinder::new(grid)
+            .find_longest_hike_length_with_only_downward_slopes()
+    }
+
+    fn part_2(&self, grid: &CharGrid) -> u32 {
+        PathFinder::new(grid).find_longest_hike_length()
+    }
+
+    fn samples(&self) {
+        aoc::puzzle_samples! {
+            self, part_1, TEST, 94,
+            self, part_2, TEST, 154
+        };
+    }
+}
+
+fn main() {
+    AoC2023_23 {}.run(std::env::args());
+}
+
+const TEST: &str = "\
+#.#####################
+#.......#########...###
+#######.#########.#.###
+###.....#.>.>.###.#.###
+###v#####.#v#.###.#.###
+###.>...#.#.#.....#...#
+###v###.#.#.#########.#
+###...#.#.#.......#...#
+#####.#.#.#######.#.###
+#.....#.#.#.......#...#
+#.#####.#.#.#########v#
+#.#...#...#...###...>.#
+#.#.#v#######v###.###v#
+#...#.>.#...>.>.#.###.#
+#####v#.#.###v#.#.###.#
+#.....#...#...#.#.#...#
+#.#########.###.#.#.###
+#...###...#...#...#.###
+###.###.#.###v#####v###
+#...#...#.#.>.>.#.>.###
+#.###.###.#.###.#.#v###
+#.....###...###...#...#
+#####################.#
+";
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    pub fn samples() {
+        AoC2023_23 {}.samples();
+    }
+}
diff --git a/src/main/rust/Cargo.lock b/src/main/rust/Cargo.lock
index 2b6d3a81..6fd154a7 100644
--- a/src/main/rust/Cargo.lock
+++ b/src/main/rust/Cargo.lock
@@ -364,6 +364,13 @@ dependencies = [
  "aoc",
 ]
 
+[[package]]
+name = "AoC2023_23"
+version = "0.1.0"
+dependencies = [
+ "aoc",
+]
+
 [[package]]
 name = "aho-corasick"
 version = "1.0.2"