diff --git a/asciiquarium_ng.py b/asciiquarium_ng.py
index 7b7f3fa..75a37a4 100755
--- a/asciiquarium_ng.py
+++ b/asciiquarium_ng.py
@@ -301,6 +301,9 @@ class Aquarium:
         self.cols    = cols
         self.cfg     = cfg or Config()
         self.canvas  = Canvas(rows, cols)
+        # wl = first row of the wave area, proportional like Perl's int($lines/3).
+        # wl+4 is the first fully-underwater row (4 wave rows below wl).
+        self.wl      = max(3, rows // 3)
         self.entities: List[Entity] = []
 
         fns = [self.add_whale, self.add_monster, self.add_swan,
@@ -324,13 +327,15 @@ class Aquarium:
     def _setup(self):
         self.entities.clear()
         self.add_environment()
-        self.add_castle()
+        if self.rows >= 20:
+            self.add_castle()
         self.add_all_seaweed()
         self.add_all_fish()
         self.random_object(None)
 
     def resize(self, rows: int, cols: int):
         self.rows, self.cols = rows, cols
+        self.wl = max(3, rows // 3)
         self.canvas.resize(rows, cols)
         self._cs_state      = 0
         self._cs_portcullis = None
@@ -368,7 +373,7 @@ class Aquarium:
             self._add(Entity(
                 frames=[[seg * repeat]],
                 masks=None,
-                x=0, y=i + 5,
+                x=0, y=self.wl + i,
                 cb_args=[0, 0, 0],
                 default_color='c',
                 die_offscreen=False,
@@ -663,7 +668,7 @@ class Aquarium:
 
         height = len(shape)
         width  = max(len(l) for l in shape)
-        y = random.randint(9, max(10, self.rows - height))
+        y = random.randint(self.wl + 4, max(self.wl + 5, self.rows - height))
 
         # Initial population (dead=None): start already on-screen so the
         # aquarium is immediately populated.  Respawned fish enter from edges.
@@ -770,7 +775,7 @@ class Aquarium:
         going_right = random.random() < 0.5
         speed = 2.0 * (1 if going_right else -1)
         x = -53 if going_right else self.cols - 2
-        y = random.randint(9, max(10, self.rows - 19))
+        y = random.randint(self.wl + 4, max(self.wl + 5, self.rows - 19))
 
         self._add(Entity(
             frames=[shape_r if going_right else shape_l],
@@ -1061,7 +1066,7 @@ BBBB          BBBBB
         else:
             x = self.cols - 1;  shape = shape_l;  mask = _rand_color(mask_l_t)
 
-        y = random.randint(9, max(10, self.rows - 15))
+        y = random.randint(self.wl + 4, max(self.wl + 5, self.rows - 15))
         self._add(Entity(
             frames=[shape], masks=[mask],
             x=x, y=y,
@@ -1119,7 +1124,7 @@ ygcgwwwww  ygcgwwwww  ygcgwwwww
 
         self._add(Entity(
             frames=shapes, masks=[mask] * 3,
-            x=x, y=5,
+            x=x, y=self.wl,
             cb_args=[speed, 0, 0, 0.25],
             default_color='W',
             die_offscreen=True,
@@ -1176,12 +1181,11 @@ ygcgwwwww  ygcgwwwww  ygcgwwwww
         base_x = -13 if going_right else self.cols - 2
 
         # Three dolphins offset in their path cycle (offsets 0, 12, 24).
-        # start_ys are the y positions at path offsets 0, 12, 24.
-        # With amplitude ±7 and center y=10 the arc spans y=3 (above waves)
-        # to y=10 (just below waterline), crossing the surface in both phases.
-        # Cumulative dy: offset 0→0, offset 12→-6, offset 24→-3
-        # so start_ys = [10, 10-6, 10-3] = [10, 4, 7]
-        start_ys = [10, 4, 7]
+        # Relative to wl so the arc crosses the surface at any terminal size.
+        # Amplitude ±7: range [wl+5-7, wl+5] = [wl-2, wl+5]
+        # → briefly above waves and ~2 rows underwater.
+        # Cumulative dy at offsets 0/12/24: 0/-6/-3
+        start_ys = [self.wl + 5, self.wl - 1, self.wl + 2]
         colors   = ['b', 'B', 'C']
         for i in range(3):
             is_lead = (i == 2)
@@ -1304,7 +1308,7 @@ ygyyy
         going_right = random.random() < 0.5
         speed = random.uniform(0.3, 0.8) * (1 if going_right else -1)
         x = -5 if going_right else self.cols - 2
-        y = random.randint(9, max(10, self.rows - 10))
+        y = random.randint(self.wl + 4, max(self.wl + 5, self.rows - 10))
         self._add(Entity(
             frames=[frame0, frame1], masks=[mask0, mask1],
             x=x, y=y,
@@ -1353,7 +1357,7 @@ mmmmmm
         going_right = random.random() < 0.5
         speed = random.uniform(0.5, 1.5) * (1 if going_right else -1)
         x = -8 if going_right else self.cols - 2
-        y = random.randint(9, max(10, self.rows - 8))
+        y = random.randint(self.wl + 4, max(self.wl + 5, self.rows - 8))
         frames = [frame_r0, frame_r1] if going_right else [frame_l0, frame_l1]
         self._add(Entity(
             frames=frames, masks=[mask_r, mask_r],
@@ -1403,7 +1407,7 @@ yccw
             x, frames, mask = -6, [diver_r0, diver_r1], mask_r
         else:
             x, frames, mask = self.cols - 2, [diver_l0, diver_l1], mask_l
-        y = random.randint(9, max(10, self.rows - 5))
+        y = random.randint(self.wl + 4, max(self.wl + 5, self.rows - 5))
 
         def on_death(e, aq):
             aq.add_bubble(e)