diff --git a/2021-python/solutions/day_01.py b/2021-python/solutions/day_01.py
new file mode 100644
index 0000000..e181a5f
--- /dev/null
+++ b/2021-python/solutions/day_01.py
@@ -0,0 +1,31 @@
+from solutions import BaseSolution
+
+
+class Solution(BaseSolution):
+    input_file = "01.txt"
+
+    def __str__(self):
+        return "Day 1: Sonar Sweep"
+
+    def parse_input(self, data):
+        return [int(n) for n in data.split()]
+
+    def solve(self, puzzle_input):
+        return sum(
+            [puzzle_input[i] > puzzle_input[i - 1] for i in range(1, len(puzzle_input))]
+        )
+
+    def solve_again(self, puzzle_input):
+        puzzle_input.append(max(puzzle_input) + 1)
+        return sum(
+            [
+                (puzzle_input[i] + puzzle_input[i - 1] + puzzle_input[i - 2])
+                > (puzzle_input[i - 1] + puzzle_input[i - 2] + puzzle_input[i - 3])
+                for i in range(2, len(puzzle_input) - 1)
+            ]
+        )
+
+
+if __name__ == "__main__":
+    solution = Solution()
+    solution.show_results()
diff --git a/2021-python/tests/test_day_01.py b/2021-python/tests/test_day_01.py
new file mode 100644
index 0000000..5a9e9d9
--- /dev/null
+++ b/2021-python/tests/test_day_01.py
@@ -0,0 +1,40 @@
+import unittest
+
+from solutions.day_01 import Solution
+
+
+class Day01TestCase(unittest.TestCase):
+    def setUp(self):
+        self.solution = Solution()
+        self.puzzle_input = self.solution.parse_input(
+            """
+        199
+200
+208
+210
+200
+207
+240
+269
+260
+263
+        """
+        )
+
+    def test_parse_puzzle_input(self):
+        data = """
+        12
+        23
+        45
+        """
+        assert self.solution.parse_input(data) == [12, 23, 45]
+
+    def test_solve_first_part(self):
+        assert self.solution.solve(self.puzzle_input) == 7
+
+    def test_solve_second_part(self):
+        assert self.solution.solve_again(self.puzzle_input) == 5
+
+
+if __name__ == "__main__":
+    unittest.main()