I have a much simpler solution by simply counting the number of 0 edges

class Solution:
  def findIslandPerimeter(self, matrix):
    # TODO: Write your code here
    perimeter = 0
    for i, column in enumerate(matrix):
      for j, elem in enumerate(column):
        if elem == 1:
          if 0 > i-1 or matrix[i-1][j] == 0:
            perimeter += 1
          if i+1 > len(matrix)-1 or matrix[i+1][j] == 0:
            perimeter += 1
          if 0 > j-1 or matrix[i][j-1] == 0:
            perimeter += 1
          if j+1 > len(column)-1 or matrix[i][j+1] == 0:
            perimeter += 1                                

    return perimeter