The Mariners are playing for pride in the final fixture of the WACA grade competition after late-season form put them out of finals contention.
Brayden Sutton (3-77) and Craig Simmons (3-102) were the best with the ball, but the Mariners will have to bat extremely well next Saturday to take any points.
Second-grade are just hanging on to their finals berth after a poor batting display against Claremont-Nedlands.
The Mariners managed just 75 in the first innings, with John Murphy (42) accounting for more than half of the small total.
Claremont-Nedlands were 4-117 at stumps, with Joel Marion (2-26) continuing his good form with the ball.
A personal best 88 from Elliot Lyons and a 60 from Jay Collard helped third-grade take day one honours.
Claremont-Nedlands bowlers kept the pressure on all day to have the Mariners out for a competitive 229.
A useful 32 from Steve Cairns helped resurrect a faltering fourth-grade batting innings.
The side was cruising at 2-80 before three quick wickets fell, but Cairns and Sid Menzes (31) helped post a reasonable score of 149.
In the remaining overs, Ganish Chaudhari (2-8) and Lachlan Harris (1-19) added some spice to the game, with the visitors slumping to 3-22 at stumps.
Baldivis players Lachlan Pratt (3-17) and Robert Botha (2-22) helped the under-17s dismiss Claremont-Nedlands for 125.
However, the good bowling work came undone with the Mariners 3-15 at stumps.