Any recommendations for developing toy drive while swimming

Hello,
I have a 2 yr old lab that obviously loves water!  She is an good jumper on land and I was working with her jumping into a pool which she is adjusting to, however, when she is in the water she could care less about the toy and just wants to swim!  She will fetch the toy and play with it in the yard but as soon as you throw it in the water she will get in and just swim all over ignoring her toy which i bought for swimming and played with her long enough to get her excited about it but she only got to have it in the pool.  She's still getting used to jumping into the pool but I don't know how to get her to "chase" a toy so that we can see if she can do the dock diving.  This is our first time trying this after we saw the event in Maumee last month and I was hoping to try it out this weekend but I'm not sure she would jump in after her toy, so to make this long story short!!!   Any recommendations on what I should try to do to get her jumping and chasing(retrieving) toys?  I really think if she could get the practice and  excitement over the toy that she could do a pretty decent job I just don't know how to get her to that stage yet!   HELP!