diff --git a/lrauv_description/models/tethys_equipped/model.sdf b/lrauv_description/models/tethys_equipped/model.sdf
index 8ed76810..e6e3df58 100644
--- a/lrauv_description/models/tethys_equipped/model.sdf
+++ b/lrauv_description/models/tethys_equipped/model.sdf
@@ -195,6 +195,7 @@
         <max_volume>0.000955</max_volume>
         <!-- m^3/s -->
         <max_inflation_rate>0.000003</max_inflation_rate>
+        <surface>0</surface>
       </plugin>
       <plugin
         filename="ignition-gazebo-detachable-joint-system"
diff --git a/lrauv_description/test/worlds/tilted_world.sdf b/lrauv_description/test/worlds/tilted_world.sdf
index 3a118b1a..b27ca428 100644
--- a/lrauv_description/test/worlds/tilted_world.sdf
+++ b/lrauv_description/test/worlds/tilted_world.sdf
@@ -17,7 +17,7 @@
 
     <physics name="1ms" type="dart">
       <max_step_size>0.02</max_step_size>
-      <real_time_factor>0</real_time_factor>
+      <real_time_factor>1</real_time_factor>
     </physics>
     <plugin
       filename="ignition-gazebo-physics-system"
@@ -35,14 +35,7 @@
     <plugin
       filename="ignition-gazebo-buoyancy-system"
       name="ignition::gazebo::systems::Buoyancy">
-      <!-- TODO: fix behaviour near surface, see https://github.com/osrf/lrauv/issues/102
-        <graded_buoyancy>
-        <default_density>1025</default_density>
-        <density_change>
-          <above_depth>5</above_depth>
-          <density>1</density>
-        </density_change>
-      </graded_buoyancy> -->
+      <!-- TODO: fix behaviour near surface, see https://github.com/osrf/lrauv/issues/102 -->
       <uniform_fluid_density>1025</uniform_fluid_density>
     </plugin>
 
diff --git a/lrauv_ignition_plugins/worlds/buoyant_tethys.sdf b/lrauv_ignition_plugins/worlds/buoyant_tethys.sdf
index 6174a4b9..8059a4a9 100644
--- a/lrauv_ignition_plugins/worlds/buoyant_tethys.sdf
+++ b/lrauv_ignition_plugins/worlds/buoyant_tethys.sdf
@@ -35,15 +35,14 @@
     <plugin
       filename="ignition-gazebo-buoyancy-system"
       name="ignition::gazebo::systems::Buoyancy">
-      <!-- TODO: fix behaviour near surface, see https://github.com/osrf/lrauv/issues/102
-        <graded_buoyancy>
+      <!-- TODO: fix behaviour near surface, see https://github.com/osrf/lrauv/issues/102-->
+      <graded_buoyancy>
         <default_density>1025</default_density>
         <density_change>
-          <above_depth>0.5</above_depth>
+          <above_depth>1</above_depth>
           <density>1</density>
         </density_change>
-      </graded_buoyancy-->
-      <uniform_fluid_density>1025</uniform_fluid_density>
+      </graded_buoyancy>
     </plugin>
 
     <!-- Requires ParticleEmitter2 in ign-gazebo 4.8.0, which will be copied
diff --git a/lrauv_ignition_plugins/worlds/empty_environment.sdf b/lrauv_ignition_plugins/worlds/empty_environment.sdf
index ce76e0bb..c345a815 100644
--- a/lrauv_ignition_plugins/worlds/empty_environment.sdf
+++ b/lrauv_ignition_plugins/worlds/empty_environment.sdf
@@ -39,7 +39,14 @@
     <plugin
       filename="ignition-gazebo-buoyancy-system"
       name="ignition::gazebo::systems::Buoyancy">
-      <uniform_fluid_density>1025</uniform_fluid_density>
+      <graded_buoyancy>
+        <default_density>1025</default_density>
+        <density_change>
+          <above_depth>0.5</above_depth>
+          <density>1</density>
+        </density_change>
+      </graded_buoyancy>
+      <!--<uniform_fluid_density>1025</uniform_fluid_density>-->
     </plugin>
 
     <!-- Requires ParticleEmitter2 in ign-gazebo 4.8.0, which will be copied
diff --git a/lrauv_ignition_plugins/worlds/multi_lrauv.sdf b/lrauv_ignition_plugins/worlds/multi_lrauv.sdf
index f019b138..6f38cf61 100644
--- a/lrauv_ignition_plugins/worlds/multi_lrauv.sdf
+++ b/lrauv_ignition_plugins/worlds/multi_lrauv.sdf
@@ -33,7 +33,14 @@
     <plugin
       filename="ignition-gazebo-buoyancy-system"
       name="ignition::gazebo::systems::Buoyancy">
-      <uniform_fluid_density>1025</uniform_fluid_density>
+      <graded_buoyancy>
+        <default_density>1025</default_density>
+        <density_change>
+          <above_depth>0.5</above_depth>
+          <density>1</density>
+        </density_change>
+      </graded_buoyancy>
+      <!--<uniform_fluid_density>1025</uniform_fluid_density>-->
     </plugin>
 
     <!-- Requires ParticleEmitter2 in ign-gazebo 4.8.0, which will be copied
@@ -101,12 +108,12 @@
     </include>
 
     <include>
-      <pose>0 0 1 0 0 1.57</pose>
+      <pose>0 0 -1 0 0 1.57</pose>
       <uri>tethys_equipped</uri>
     </include>
 
     <include>
-      <pose>5 0 1 0 0 1.57</pose>
+      <pose>5 0 -1 0 0 1.57</pose>
       <uri>tethys_equipped</uri>
       <name>triton</name>
 
@@ -149,7 +156,7 @@
     </include>
 
     <include>
-      <pose>-5 0 1 0 0 1.57</pose>
+      <pose>-5 0 -1 0 0 1.57</pose>
       <uri>tethys_equipped</uri>
       <name>daphne</name>
 
@@ -193,15 +200,16 @@
 
     <!-- Swimming race lane signs -->
     <include>
-      <pose>0 0 -1 0 0 3.1415926</pose>
+      <pose>0 0 -2 0 0 3.1415926</pose>
       <uri>ABCSign_5m</uri>
       <name>start_line</name>
     </include>
     <include>
-      <pose>0 -25 -1 0 0 3.1415926</pose>
+      <pose>0 -25 -2 0 0 3.1415926</pose>
       <uri>ABCSign_5m</uri>
       <name>finish_line</name>
     </include>
 
   </world>
 </sdf>
+ 
\ No newline at end of file