Island count - using queue - I wrote a bug on line 47 and 50 to mix visitRow and visitCol with startRow and startCol. Next time it is important to declare new variables for visitRow, visitCol, otherwise I may mix things together. Build a good habit.

IslandCount_UsingQueue.cs

using System;
using System.Collections.Generic;

class Solution
{
    public static int GetNumberOfIslands(int[,] binaryMatrix)
    {
      if(binaryMatrix == null)
        return 0; 
      
      var rows    = binaryMatrix.GetLength(0); 
      var columns = binaryMatrix.GetLength(1); 
      
      int countIsland = 0; 
      
      for(int row = 0; row < rows; row++)
      {
        for(int col = 0 ; col < columns; col++)
        {
          var current = binaryMatrix[row, col]; 
          if(current != 1)
            continue;
          
          visitNeighbors(binaryMatrix, row, col); 
          
          countIsland++; 
        }
      }
      
      return countIsland;
    }
  
    private static void visitNeighbors(int[,] matrix, int startRow, int startCol)
    {
       var queue =  new Queue<int[]>(); 
       queue.Enqueue(new int[]{startRow, startCol}); 
      
       while(queue.Count > 0)
       {
         var visitNode = queue.Dequeue(); 
         
         var visitRow = visitNode[0];
         var visitCol = visitNode[1]; 
         
         matrix[visitRow, visitCol] = -1; // mark visited
         
         pushNeighborToQueue(queue, matrix, visitRow,     visitCol - 1); // left
         pushNeighborToQueue(queue, matrix, visitRow,     visitCol + 1); // right
         pushNeighborToQueue(queue, matrix, visitRow - 1, visitCol); // up
         pushNeighborToQueue(queue, matrix, visitRow + 1, visitCol); // down
       }
    }
  
    private static void pushNeighborToQueue(Queue<int[]> queue, int[,] matrix, int startRow, int startCol)
    {
       var rows = matrix.GetLength(0); 
       var columns = matrix.GetLength(1); 
      
       if(startRow < 0 || startRow >= rows || startCol < 0 || startCol >= columns || matrix[startRow, startCol] != 1)
       {
         return; 
       }
      
       queue.Enqueue(new int[]{startRow, startCol});      
    }

    static void Main(string[] args)
    {
    }
}

/*
0 -1   0  -1   0 
0  0  -1  -1   -1
C  0  0   -1  0
0 D   -1    0 0 
E 0  -1 0 F  
  
  countOfIsland  1 - A
                 1 - B
                 
                 6 - A, B, C, D, E, F
                 BFS search / queue -> 
  */

I was lazy and do not declare two variables visitRow and visitCol, and then I mix startRow with visiitRow, startCol with visitCol. I wrote the code and forgot to push four neighbors into queue.
I finished the coding in less than 17 minutes, and I failed 3 test cases. It took me one minute to find the bug from line 47 to line 50. I fixed it in less than one minute.