Where are the issues?

- Seats are bouncy again
- Seats can be mounted again
- Fixed increased water fog while wearing Diving helmet

src/main/java/com/simibubi/create/AllEntityTypes.java

@@ -52,7 +52,7 @@ public class AllEntityTypes {
 			MobCategory.MISC, 4, 20, true, false, PotatoProjectileEntity::build).register();
 
 	public static final EntityEntry<SeatEntity> SEAT = register("seat", SeatEntity::new, () -> SeatEntity.Render::new,
-		MobCategory.MISC, 0, Integer.MAX_VALUE, false, true, SeatEntity::build).register();
+		MobCategory.MISC, 5, Integer.MAX_VALUE, false, true, SeatEntity::build).register();
 
 	//
 

src/main/java/com/simibubi/create/content/contraptions/components/actors/SeatBlock.java

@@ -29,6 +29,7 @@ import net.minecraft.world.level.pathfinder.BlockPathTypes;
 import net.minecraft.world.level.pathfinder.PathComputationType;
 import net.minecraft.world.phys.AABB;
 import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
 import net.minecraft.world.phys.shapes.CollisionContext;
 import net.minecraft.world.phys.shapes.VoxelShape;
 
@@ -60,8 +61,19 @@ public class SeatBlock extends Block {
 	@Override
 	public void updateEntityAfterFallOn(BlockGetter reader, Entity entity) {
 		BlockPos pos = entity.blockPosition();
-		if (entity instanceof Player || !(entity instanceof LivingEntity) || !canBePickedUp(entity) || isSeatOccupied(entity.level, pos)) {
-			super.updateEntityAfterFallOn(reader, entity);
+		if (entity instanceof Player || !(entity instanceof LivingEntity) || !canBePickedUp(entity)
+			|| isSeatOccupied(entity.level, pos)) {
+			if (entity.isSuppressingBounce()) {
+				super.updateEntityAfterFallOn(reader, entity);
+				return;
+			}
+
+			Vec3 vec3 = entity.getDeltaMovement();
+			if (vec3.y < 0.0D) {
+				double d0 = entity instanceof LivingEntity ? 1.0D : 0.8D;
+				entity.setDeltaMovement(vec3.x, -vec3.y * (double) 0.66F * d0, vec3.z);
+			}
+
 			return;
 		}
 		if (reader.getBlockState(pos)
@@ -71,8 +83,7 @@ public class SeatBlock extends Block {
 	}
 
 	@Override
-	public BlockPathTypes getAiPathNodeType(BlockState state, BlockGetter world, BlockPos pos,
-		@Nullable Mob entity) {
+	public BlockPathTypes getAiPathNodeType(BlockState state, BlockGetter world, BlockPos pos, @Nullable Mob entity) {
 		return BlockPathTypes.RAIL;
 	}
 
@@ -99,7 +110,8 @@ public class SeatBlock extends Block {
 		if (color != null && color != this.color) {
 			if (world.isClientSide)
 				return InteractionResult.SUCCESS;
-			BlockState newState = BlockHelper.copyProperties(state, AllBlocks.SEATS.get(color).getDefaultState());
+			BlockState newState = BlockHelper.copyProperties(state, AllBlocks.SEATS.get(color)
+				.getDefaultState());
 			world.setBlockAndUpdate(pos, newState);
 			return InteractionResult.sidedSuccess(world.isClientSide);
 		}
@@ -136,7 +148,7 @@ public class SeatBlock extends Block {
 		if (world.isClientSide)
 			return;
 		SeatEntity seat = new SeatEntity(world, pos);
-		seat.setPosRaw(pos.getX() + .5f, pos.getY(), pos.getZ() + .5f);
+		seat.setPos(pos.getX() + .5f, pos.getY(), pos.getZ() + .5f);
 		world.addFreshEntity(seat);
 		entity.startRiding(seat, true);
 	}

src/main/java/com/simibubi/create/content/contraptions/components/actors/SeatEntity.java

@@ -12,6 +12,7 @@ import net.minecraft.network.protocol.Packet;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.entity.EntityType;
+import net.minecraft.world.entity.LivingEntity;
 import net.minecraft.world.level.Level;
 import net.minecraft.world.phys.AABB;
 import net.minecraft.world.phys.Vec3;
@@ -35,7 +36,7 @@ public class SeatEntity extends Entity implements IEntityAdditionalSpawnData {
 		EntityType.Builder<SeatEntity> entityBuilder = (EntityType.Builder<SeatEntity>) builder;
 		return entityBuilder.sized(0.25f, 0.35f);
 	}
-	
+
 	@Override
 	public void setPos(double x, double y, double z) {
 		super.setPos(x, y, z);
@@ -49,7 +50,7 @@ public class SeatEntity extends Entity implements IEntityAdditionalSpawnData {
 
 	@Override
 	public void tick() {
-		if (level.isClientSide) 
+		if (level.isClientSide)
 			return;
 		boolean blockPresent = level.getBlockState(blockPosition())
 			.getBlock() instanceof SeatBlock;
@@ -60,15 +61,19 @@ public class SeatEntity extends Entity implements IEntityAdditionalSpawnData {
 
 	@Override
 	protected boolean canRide(Entity entity) {
-		// Fake Players (tested with deployers) have a BUNCH of weird issues, don't let them ride seats
+		// Fake Players (tested with deployers) have a BUNCH of weird issues, don't let
+		// them ride seats
 		return !(entity instanceof FakePlayer);
 	}
 
 	@Override
 	protected void removePassenger(Entity entity) {
 		super.removePassenger(entity);
-		Vec3 pos = entity.position();
-		entity.setPos(pos.x, pos.y + 0.85f, pos.z);
+	}
+
+	@Override
+	public Vec3 getDismountLocationForPassenger(LivingEntity pLivingEntity) {
+		return super.getDismountLocationForPassenger(pLivingEntity).add(0, 0.5f, 0);
 	}
 
 	@Override
@@ -92,7 +97,8 @@ public class SeatEntity extends Entity implements IEntityAdditionalSpawnData {
 		}
 
 		@Override
-		public boolean shouldRender(SeatEntity p_225626_1_, Frustum p_225626_2_, double p_225626_3_, double p_225626_5_, double p_225626_7_) {
+		public boolean shouldRender(SeatEntity p_225626_1_, Frustum p_225626_2_, double p_225626_3_, double p_225626_5_,
+			double p_225626_7_) {
 			return false;
 		}
 

src/main/java/com/simibubi/create/events/ClientEvents.java

@@ -303,7 +303,7 @@ public class ClientEvents {
 
 		if (FluidHelper.isWater(fluid) && AllItems.DIVING_HELMET.get()
 			.isWornBy(Minecraft.getInstance().cameraEntity)) {
-			event.setDensity(0.010f);
+			event.setDensity(300f);
 			event.setCanceled(true);
 			return;
 		}