4800 yds

600 standard warm-up
2x   300 pull or swim Descend by 100
       3x100 hold a fast pace
       300 pull or swim (50 fast, 50 recovery)
       4x150 (100 medium, 50 non-free fast)
       300 pull or swim
       6x50 odds: fast, evens: recovery all on the same interval