diff --git a/pyroms_tools/grid/edit_grid_mask.py b/pyroms_tools/grid/edit_grid_mask.py
new file mode 100644
index 0000000..a2322a9
--- /dev/null
+++ b/pyroms_tools/grid/edit_grid_mask.py
@@ -0,0 +1,35 @@
+from pyroms_tools.utils import edit_mask as em
+from pyroms_tools.utils import utils as ut
+import xarray as xr
+from scipy.ndimage import label
+import numpy as np
+
+
+def largest_contiguous_ocean_mask(matrix):
+    # Create a mask where True represents non-NaN elements
+    mask = matrix == 1
+    
+    # Label contiguous blocks of True values
+    labeled_array, num_features = label(mask)
+        
+        # Count the size of each contiguous region
+    # Label contiguous regions
+    labeled_mask, num_features = label(mask)
+
+    # Find the largest contiguous region
+    largest_region_label = np.argmax(np.bincount(labeled_mask.flat)[1:]) + 1  # ignore the 0 label (background)
+
+    # Create a new matrix that only includes the largest region
+    largest_region = np.where(labeled_mask == largest_region_label, matrix, False)
+
+    
+    return largest_region
+
+if __name__ == '__main__':
+    # ds = xr.open_dataset('/mnt/34c919f6-6617-49de-a20f-05e4186230b9/Dropbox/trabalho_irado/Northeastern/other/roms_grid01_smooth.nc')
+    ds = xr.open_dataset('roms_grid01_smooth.nc')
+    ds.mask_rho.values = largest_contiguous_ocean_mask(ds.mask_rho.values)
+
+    em.main(ds.mask_rho.values, ds.lat_rho.values, ds.lon_rho.values)
+
+    ds = ut.update_mask(ds)
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diff --git a/pyroms_tools/utils/edit_mask.py b/pyroms_tools/utils/edit_mask.py
new file mode 100644
index 0000000..5e40d39
--- /dev/null
+++ b/pyroms_tools/utils/edit_mask.py
@@ -0,0 +1,79 @@
+import numpy as np
+import matplotlib.pyplot as plt
+import cartopy.crs as ccrs
+import cartopy.feature as cfeature
+
+
+def find_nearest_idx(lon_array, lat_array, lon_value, lat_value):
+    """
+    Find the indices of the nearest point in the 2D lon and lat arrays to the given lon and lat values.
+    
+    Parameters:
+    - lon_array (np.ndarray): 2D array of longitudes.
+    - lat_array (np.ndarray): 2D array of latitudes.
+    - lon_value (float): Reference longitude.
+    - lat_value (float): Reference latitude.
+    
+    Returns:
+    - (int, int): Indices (j, i) of the nearest point.
+    """
+    # Calculate the squared distance to avoid computing the square root
+    dist_squared = (lon_array - lon_value)**2 + (lat_array - lat_value)**2
+    j, i = np.unravel_index(dist_squared.argmin(), dist_squared.shape)
+    return j, i
+
+def on_click(event, matrix, lat, lon, pc):
+    if event.inaxes:  # Only change values if editing mode is active
+        # Convert click coordinates (lon, lat) to matrix indices
+        lon_clicked, lat_clicked = event.xdata, event.ydata
+        y_idx, x_idx = find_nearest_idx(lon, lat, lon_clicked, lat_clicked)
+
+        # Toggle the value at the clicked position
+        matrix[y_idx, x_idx] = not matrix[y_idx, x_idx]
+
+        # Update the pcolormesh object with the new data
+        pc.set_array(matrix.ravel())
+        pc.set_clim([matrix.min(), matrix.max()])  # Adjust color limits if needed
+        plt.draw()
+
+def on_key(event, editing_mode):
+    if event.key == 'e':  # Press 'e' to toggle editing mode
+        editing_mode[0] = not editing_mode[0]
+        print(f"Editing mode {'ON' if editing_mode[0] else 'OFF'}")
+
+def main(matrix, lat, lon):
+    editing_mode = [False]  # Initially, editing mode is off
+
+    # Set up the figure with Cartopy's projection
+    fig, ax = plt.subplots(subplot_kw={'projection': ccrs.PlateCarree()})
+    ax.set_global()  # Show the whole world map
+
+    # Add initial land contours and coastlines
+    ax.add_feature(cfeature.LAND, edgecolor='black')
+    ax.coastlines()
+
+    # Overlay the matrix on top of the Cartopy map using pcolormesh
+    pc = ax.pcolormesh(lon, lat, matrix, cmap='gray', transform=ccrs.PlateCarree(), shading='auto', alpha=0.5, edgecolors='black', linewidth=0.5)
+
+    ax.grid(True, which='both', color='black', linestyle='-', linewidth=0.5)  # Draw gridlines
+
+    # Connect the click event to the on_click function
+    fig.canvas.mpl_connect('button_press_event', lambda event: on_click(event, matrix, lat, lon, pc))
+
+    # Connect the key press event to the on_key function for toggling editing mode
+    fig.canvas.mpl_connect('key_press_event', lambda event: on_key(event, editing_mode))
+
+    plt.show()
+    return matrix
+
+if __name__ == "__main__":
+    # Create a large numpy boolean matrix (e.g., representing lat/lon grid)
+    matrix = np.zeros((180, 720), dtype=bool)
+
+    # Define latitude and longitude ranges corresponding to the matrix
+    lat = np.linspace(90, -90, matrix.shape[0])  # Latitudes from 90 to -90
+    lon = np.linspace(-180, 180, matrix.shape[1])  # Longitudes from -180 to 180
+    xm,ym = np.meshgrid(lon,lat)    
+
+    main(matrix, xm, ym)
+    
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